Filed Pursuant to Rule 424(b)(5)
File Number 333-224558-01
File Number 333-224558

The information in this preliminary prospectus supplement is not complete and may be changed. A registration statement relating to these securities became automatically effective when it was filed with the Securities and Exchange Commission. Neither this preliminary prospectus supplement nor the accompanying prospectus is an offer to sell the securities described herein and neither is soliciting any offer to buy these securities in any jurisdiction where the solicitation, offer or sale is not permitted.

Subject to Completion, Dated August 6, 2018

Preliminary Prospectus Supplement to Prospectus dated May 1, 2018

American Water Capital Corp.

$             % Senior Notes due 2028

$             % Senior Notes due 2048

This is an offering by American Water Capital Corp., which is referred to as AWCC or the issuer, of its     % Senior Notes due 2028, which are referred to as the 2028 Notes, and its     % Senior Notes due 2048, which are referred to as the 2048 Notes, and together with the 2028 Notes, the notes. The issuer will pay interest semi-annually in arrears on the notes on March 1 and September 1 of each year, beginning on March 1, 2019. The 2028 Notes will mature on September 1, 2028. The 2048 Notes will mature on September 1, 2048. However, the issuer may at any time and from time to time redeem all or a portion of the notes, in each case at the applicable redemption prices set forth in this prospectus supplement under “Description of the Notes—Optional Redemption by the Issuer.” The notes will be issued only in registered form and in denominations of $1,000 and integral multiples of $1,000 in excess thereof.

The notes will be unsecured, will rank equally in right of payment with the issuer’s existing and future senior debt and will rank senior to the issuer’s future subordinated debt. The notes will rank effectively junior in right of payment to all of the issuer’s future secured indebtedness to the extent of the value of the assets securing such indebtedness. The notes will have the benefit of a support agreement from American Water Works Company, Inc., the issuer’s parent company. The notes will not be guaranteed by any of American Water Works Company, Inc.’s subsidiaries. The issuer is a finance subsidiary whose activities are limited to borrowing funds through the issuance of debt securities and lending those funds under loan agreements with American Water Works Company, Inc. and its regulated operating subsidiaries.

Investing in these notes involves risks. See “Risk Factors” beginning on page S-7 of this prospectus supplement to read about factors you should consider before buying these notes.

Neither the Securities and Exchange Commission nor any state securities commission or other regulatory body has approved or disapproved of these securities or passed upon the adequacy or accuracy of this prospectus supplement or the accompanying prospectus. Any representation to the contrary is a criminal offense.

The underwriters expect to deliver the notes in book-entry form only through the facilities of The Depository Trust Company for the accounts of its participants, including Clearstream Banking, société anonyme, and Euroclear Bank S.A./N.V., as operator of the Euroclear system, against payment in New York, New York on or about August     , 2018.

Joint Book-Running Managers

Co-Managers

Prospectus Supplement dated August     , 2018.

TABLE OF CONTENTS

PROSPECTUS

ABOUT THIS PROSPECTUS SUPPLEMENT

All references in this prospectus supplement to “American Water” and the “Company” refer to American Water Works Company, Inc. and its consolidated subsidiaries unless the context otherwise requires. All references in this prospectus supplement to the “support provider” refer to American Water Works Company, Inc., without its subsidiaries, unless the context otherwise requires. All references in this prospectus supplement to “AWCC” or the “issuer” refer to American Water Capital Corp.

This document is in two parts. The first part is this prospectus supplement, which describes the specific terms of this offering and certain other matters. The second part, the accompanying prospectus, gives more general information about the issuer, American Water and their securities. Generally, the reference to “this prospectus,” is to both parts of this document combined. To the extent information in this prospectus supplement conflicts with information in the accompanying prospectus, you should rely on the information in this prospectus supplement.

Neither AWCC nor American Water is making an offer or sale of these securities in any jurisdiction where the offer or sale is not permitted. The information which appears in this prospectus and any document incorporated by reference is accurate as of their respective dates. American Water’s business, financial condition, results of operations and prospects may have changed since the date of such information.

“American Water” and its logos are trademarks of American Water. Other service marks, trademarks and trade names referred to in this prospectus are the property of their respective owners.

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WHERE YOU CAN FIND MORE INFORMATION

American Water files annual, quarterly and current reports, proxy statements and other information with the Securities and Exchange Commission, which is referred to as the SEC. These SEC filings are available to the public over the Internet at the SEC’s website at www.sec.gov and American Water’s website at https://amwater.com. You may also read and copy any document American Water and the issuer files with the SEC at the SEC’s public reference room at 100 F Street, N.E., Washington, D.C. 20549. Please call the SEC at 1-800-SEC-0330 for further information on the public reference room. The information contained on or accessible from American Water’s website does not constitute a part of this prospectus and is not incorporated by reference herein.

American Water and the issuer have filed a registration statement on Form S-3 under the Securities Act of 1933, as amended, which is referred to as the Securities Act, with the SEC to register the securities offered by this prospectus supplement. This prospectus does not contain all the information contained in the registration statement because certain parts of the registration statement are omitted in accordance with the rules and regulations of the SEC. The registration statement and the documents filed as exhibits to the registration statement are available for inspection and copying as described above.

American Water is “incorporating by reference” into this prospectus specific documents that it files with the SEC, which means that important information can be disclosed to you by referring you to those documents that are considered part of this prospectus. Information that American Water files subsequently with the SEC will automatically update and supersede this information. American Water incorporates by reference the documents listed below, and any future documents that it files with the SEC under Section 13(a), 13(c), 14 or 15(d) of the Securities Exchange Act of 1934, as amended, which is referred to as the Exchange Act, until the offering of the securities covered by this prospectus has been completed or terminated. This prospectus is part of a registration statement filed with the SEC.

American Water is “incorporating by reference” into this prospectus the following documents filed with the SEC (excluding any portions of such documents that have been “furnished” but not “filed” for purposes of the Exchange Act):

American Water will provide to each person, including any beneficial owner, to whom this prospectus is delivered, upon written or oral request and without charge, a copy of the documents referred to above that have been incorporated in this prospectus by reference. You can request copies of such documents if you call or write American Water at the following address or telephone number: American Water Works Company, Inc., 1025 Laurel Oak Road, Voorhees, New Jersey 08043, Attention: General Counsel, (856) 346-8200.

This prospectus contain summaries of certain agreements that American Water has filed as exhibits to various SEC filings, as well as certain agreements that American Water and the issuer will enter into in connection with this offering. The descriptions of these agreements contained in this prospectus or information incorporated by reference herein do not purport to be complete and are subject to, or qualified in their entirety by reference to, the definitive agreements. You can obtain copies of the definitive agreements without charge to you by making a written or oral request to American Water.

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American Water and the issuer are only responsible for the information contained or incorporated by reference in this prospectus supplement and the accompanying prospectus or contained in any free writing prospectus prepared by or on behalf of American Water and the issuer. Neither American Water nor the issuer has authorized anyone to provide you with different information, and American Water and the issuer take no responsibility for any other information that others may give you. You should not assume that the information in this prospectus supplement or in the accompanying prospectus is accurate as of any date other than the date on the front of those documents or that the information incorporated by reference is accurate as of any date other than the date of the document incorporated by reference in this prospectus supplement or the accompanying prospectus.

Any statement contained herein or in a document incorporated or deemed to be incorporated by reference herein shall be deemed to be modified or superseded for purposes of this prospectus to the extent that a statement contained herein, in any other subsequently filed document which also is or is deemed to be incorporated by reference herein, modifies or supersedes such statement. Any such statement so modified or superseded shall not be deemed, except as so modified and superseded, to constitute a part of this prospectus.

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FORWARD-LOOKING STATEMENTS

American Water has made statements under “Risk Factors” and in other sections of this prospectus and in the documents incorporated by reference herein that are forward-looking statements within the meaning of Section 27A of the Securities Act, Section 21E of the Exchange Act, and the Private Securities Litigation Reform Act of 1995. In some cases, these forward-looking statements can be identified by words with prospective meanings such as “intend,” “plan,” “estimate,” “believe,” “anticipate,” “expect,” “predict,” “project,” “propose,” “assume,” “forecast,” “likely,” “uncertain,” “outlook,” “future,” “pending,” “goal,” “objective,” “potential,” “continue,” “seek to,” “may,” “can,” “should,” “will” and “could” or the negative of such terms or other variations or similar expressions. Forward-looking statements may relate to, among other things, American Water’s future financial performance, including its operation and maintenance efficiency ratio, its cash flows, its growth and portfolio optimization strategies, its projected capital expenditures and related funding requirements, its ability to repay debt, its projected strategy to finance current operations and growth initiatives, the impact of legal and regulatory proceedings and potential fines and penalties, business process and technology improvement initiatives, trends in American Water’s industry, regulatory, legislative, tax policy or legal developments or rate adjustments, including rate case filings, filings for infrastructure surcharges and filings to address regulatory lag, and impacts that the Tax Cuts and Jobs Act (the “TCJA”) may have on American Water and its business, results of operations, cash flows and liquidity.

Forward-looking statements are predictions based on American Water’s current expectations and assumptions regarding future events. They are not guarantees or assurances of any outcomes, financial results or levels of activity, performance or achievements, and you are cautioned not to place undue reliance upon them. These forward-looking statements are subject to a number of estimates and assumptions, and known and unknown risks, uncertainties and other factors. American Water’s actual results may vary materially from those discussed in the forward-looking statements included in this prospectus and in the documents incorporated by reference herein. Factors that could cause actual results to differ from those discussed in forward-looking statements include, but are not limited to, the factors discussed under “Risk Factors” in this prospectus supplement, and the following important factors:

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These forward-looking statements are qualified by, and should be read together with, the factors discussed under “Risk Factors” beginning on page S-7 of this prospectus supplement and the risk factors and other statements contained in the documents incorporated by reference in this prospectus and investors should refer to such risks, uncertainties, risk factors and other statements in evaluating such forward-looking statements. Any forward-looking statements made by American Water speak only as of the date of such statements. Except as required by the federal securities laws, American Water does not have any obligation, and American Water specifically disclaims any undertaking or intention to publicly update or revise any forward-looking statements, whether as a result of new information, future events, changed circumstances or otherwise. New factors emerge from time to time, and it is not possible for American Water to predict all such factors. Furthermore, it may not be possible to assess the impact of any such factor on American Water’s businesses, either viewed independently or together, or the extent to which any factor, or combination of factors, may cause results to differ materially from those contained in any forward-looking statement. The foregoing factors should not be construed as exhaustive.

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RISK FACTORS

An investment in the notes involves risks. This prospectus does not describe all of these risks. You should carefully consider the risks described below and the risks described in Part I, Item 1A, “Risk Factors,” in American Water’s Annual Report on Form 10-K for the year ended December 31, 2017, as updated in subsequently filed reports with the SEC, which risk factors and subsequently filed reports are incorporated by reference herein, as well as the other information included or incorporated by reference in this prospectus, before making an investment decision. American Water’s business, financial condition or results of operations could be materially adversely affected by any of these risks.

The issuer’s ability to service its debt and American Water’s ability to make payments pursuant to its obligations under the support agreement depend on the performance of American Water’s operating subsidiaries and their continued ability to make distributions to American Water or repayments to the issuer. There can be no assurance that American Water or the issuer will continue to receive such distributions or repayments or, if they are received, that they will be in amounts similar to past distributions or repayments.

The notes are being issued by AWCC, American Water’s finance subsidiary. The issuer has no substantial assets, other than American Water’s obligations and those of American Water’s operating subsidiaries to repay loans made by AWCC. American Water has entered into a support agreement with the issuer pursuant to which it has agreed to pay to any debt investor or lenders of the issuer any principal or interest amounts owed by the issuer to such debt investor or lender that the issuer fails to pay on a timely basis. Because substantially all of American Water’s operations are conducted through its subsidiaries other than the issuer, American Water’s ability to fulfill its obligations under the support agreement will be dependent upon its receipt of sufficient cash distributions from its operating subsidiaries. Similarly, the issuer’s ability to make interest and principal payments on the notes will be dependent upon its receipt of sufficient payments of principal and interest pursuant to the terms of its loans to American Water and its operating subsidiaries. The distributions American Water receives from its operating subsidiaries and the repayments the issuer receives from American Water and its operating subsidiaries might not be adequate to permit American Water to make required payments of interest and principal pursuant to the support agreement or the issuer to make required payments under the notes, as applicable, on a timely basis, or at all.

American Water’s obligations under the support agreement are effectively subordinated to all of the obligations of its subsidiaries other than the issuer.

American Water has entered into a support agreement with the issuer. The notes are not guaranteed by any of American Water’s subsidiaries and are the obligations only of the issuer and American Water, by virtue of the support agreement. American Water is a holding company that derives substantially all of its income from its operating subsidiaries, and the issuer is a finance subsidiary with no material operations of its own, other than making loans to American Water and its affiliates. American Water’s operating subsidiaries are separate and distinct legal entities and, other than the issuer, have no obligation to make any payments on the notes or to make any funds available for such payment. Therefore, American Water’s obligations under the support agreement will be effectively subordinated to all indebtedness and other liabilities, including trade payables, lease commitments and moneys borrowed, incurred or issued by American Water’s subsidiaries other than the issuer.

The notes do not restrict American Water’s ability to incur additional indebtedness, which could adversely affect its ability to pay its obligations under the notes.

Although the terms of the notes restrict American Water’s ability and the ability of its subsidiaries to incur certain liens and to enter into certain sale and leaseback transactions, the incurrence of other indebtedness or other liabilities by any of American Water’s subsidiaries is not specifically prohibited in connection with the notes and could adversely affect American Water’s ability to pay its obligations on the notes. As of June 30, 2018, total liabilities of American Water’s subsidiaries other than the issuer were $1,346 million, consisting of (i)

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$722 million in private activity bonds and government funded debt, of which $715 million is collateralized, (ii) $606 million in mortgage bonds, and (iii) $18 million in mandatory redeemable preferred stock, capital lease obligations and other term loans. American Water anticipates that from time to time its subsidiaries will incur additional debt and other liabilities. Any debt incurred by American Water’s subsidiaries other than the issuer will be effectively senior to American Water’s obligations under the support agreement.

Other than as described under “Description of AWCC Debt Securities and American Water Support Agreement—Support Agreement” in the accompanying prospectus, neither the issuer nor American Water is required in connection with the notes to meet any financial tests that measure their working capital, interest coverage or fixed charges in order to maintain compliance with the terms of the notes.

If there is no active trading market for the notes you may not be able to resell them.

If there is no active trading market for the notes, you may not be able to resell the notes at their fair market value or at all.

The liquidity of any market for the notes will depend upon various factors, including:

Accordingly, neither American Water nor the issuer can assure you that a market or liquidity will develop for the notes.

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USE OF PROCEEDS

The issuer estimates that it will receive net proceeds of approximately $        million from this offering, after deducting underwriting discounts and estimated offering expenses.

The issuer intends to use the net proceeds from this offering:

On August 3, 2018, the issuer had $1,569.7 million in aggregate principal amount of commercial paper outstanding, with a weighted-average maturity of 14 days and a weighted-average annual interest rate of 2.46%.

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RATIOS OF EARNINGS TO FIXED CHARGES

For purposes of calculating the ratio of earnings to fixed charges, earnings consist of income from continuing operations before income taxes including the effect of AFUDC, plus fixed charges. Fixed charges consist of interest expense, amortization of debt issuance costs, and a portion of rent expense that management believes is representative of the interest component of rental expense. Fixed charges have not been reduced for the effect of AFUDC.

American Water’s and the issuer’s ratios of earnings to fixed charges for each of the periods indicated were as follows:

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DESCRIPTION OF THE NOTES

The following description is a summary of the material provisions of the indenture. It does not restate such agreement in its entirety. You are urged to read the indenture because it, and not this description, defines your rights as holders of the notes. The indenture was filed as an exhibit to the registration statement of which this prospectus forms a part.

The notes will be three separate, new series of Debt Securities, as described under the heading “Description of AWCC Debt Securities and American Water Support Agreement” in the accompanying prospectus. Please read the following information concerning the notes in conjunction with the statements under “Description of AWCC Debt Securities and American Water Support Agreement” in the accompanying prospectus, which the following information supplements and, in the event of any inconsistencies, supersedes.

Unless the context otherwise requires, solely for purposes of this Description of the Notes, “American Water” or the “Company” refers to American Water Works Company, Inc. and not to any of its subsidiaries.

General

The notes will be issued under the indenture, dated as of December 4, 2009, between the issuer and Wells Fargo Bank, National Association, as indenture trustee, referred to as the indenture.

The aggregate principal amount of the 2028 Notes offered by this prospectus supplement is $        . The aggregate principal amount of the 2048 Notes offered by this prospectus supplement is $        .

The notes will have the benefit of a support agreement from American Water described in this prospectus.

The notes will be the issuer’s unsecured senior obligations and will:

Similarly, American Water’s obligations as support provider under the support agreement will be unsecured senior obligations of American Water and will:

The notes will not be subject to a sinking fund provision.

The indenture trustee will initially be the security registrar and the paying agent for the notes. The notes initially will be issued in registered global form and will be in denominations of $1,000 and integral multiples of $1,000 in excess thereof, without coupons, and may be transferred or exchanged, without service charge but upon

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payment of any taxes or other governmental charges payable in connection with the transfer or exchange, at the office described below. Payments on notes issued as a global security will be made to the depositary or a successor depositary. A beneficial interest in a global note may only be exchanged for a note in certificated form in certain circumstances. See “Description of AWCC Debt Securities and American Water Support Agreement—Book-Entry, Delivery and Form—Exchanges of Global Securities for Certificated Debt Securities” in the accompanying prospectus and “—Book-Entry Only Issuance” in this prospectus supplement. Principal and interest with respect to certificated notes will be payable thereon, the transfer of the notes will be registrable and notes will be exchangeable for notes of a like aggregate principal amount in denominations of $1,000, and integral multiples of $1,000 in excess thereof, at the office or agency maintained by the issuer. The issuer has initially designated the corporate trust office of the indenture trustee as that office. However, at the issuer’s option, payment of interest may be made by check mailed to the address of the holder entitled to payment or by wire transfer to an account appropriately designated by the holder entitled to payment.

The indenture does not limit American Water’s ability or the ability of the issuer to issue or incur other unsecured debt or issue preferred stock.

Principal, Maturity and Interest

2028 Notes

The initial aggregate principal amount of the 2028 Notes is $            . The 2028 Notes mature on September 1, 2028.

The 2028 Notes will bear interest at     % per annum from August     , 2018. The issuer will pay interest on the 2028 Notes semi-annually in arrears on each March 1 and September 1, beginning on March 1, 2019, to the holders of the 2028 Notes as of the day that is 15 calendar days (whether or not a business day) prior to the relevant interest payment date and, if applicable, upon redemption.

2048 Notes

The initial aggregate principal amount of the 2048 Notes is $            . The 2048 Notes mature on September 1, 2048.

The 2048 Notes will bear interest at     % per annum from August     , 2018. The issuer will pay interest on the 2048 Notes semi-annually in arrears on each March 1 and September 1, beginning on March 1, 2019, to the holders of the 2048 Notes as of the day that is 15 calendar days (whether or not a business day) prior to the relevant interest payment date and, if applicable, upon redemption.

Computation of Interest

The amount of interest payable on the notes for any period will be computed on the basis of a 360-day year consisting of twelve 30-day months. In the event that any date on which principal or interest is payable on the notes is not a business day, then payment of the principal or interest payable on such date will be made on the next day that is a business day (and without any interest or other payment in respect of any such delay).

Optional Redemption by the Issuer

2028 Notes

The issuer may redeem all or a portion of the 2028 Notes at the issuer’s option at any time or from time to time. The redemption price for the 2028 Notes to be redeemed on any redemption date prior to June 1, 2028 will be equal to the greater of the following amounts:

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plus, in each case, accrued and unpaid interest thereon to the redemption date. The redemption price for the 2028 Notes to be redeemed on any redemption date on or after June 1, 2028 will be equal to 100% of the principal amount to be redeemed plus any accrued and unpaid interest thereon to the date of redemption. Interest payable on the 2028 Notes with respect to an interest payment date that falls on or before a redemption date shall be made to the holder of such 2028 Notes on the record date related to such interest payment date. The redemption price will be calculated on the basis of a 360-day year consisting of twelve 30-day months. Calculation of the redemption price will be made by the issuer or on its behalf by such person as it will designate. Such calculation or the correctness thereof will not be a duty or obligation of the indenture trustee.

On and after the date of redemption, interest will cease to accrue on the 2028 Notes or portion of the 2028 Notes redeemed. However, interest will continue to accrue if the issuer defaults in the payment of the amount due upon redemption.

2048 Notes

The issuer may redeem all or a portion of the 2048 Notes at the issuer’s option at any time or from time to time. The redemption price for the 2048 Notes to be redeemed on any redemption date prior to March 1, 2048 will be equal to the greater of the following amounts:

plus, in each case, accrued and unpaid interest thereon to the redemption date. The redemption price for the 2048 Notes to be redeemed on any redemption date on or after March 1, 2048 will be equal to 100% of the principal amount to be redeemed plus any accrued and unpaid interest thereon to the date of redemption. Interest payable on the 2048 Notes with respect to an interest payment date that falls on or before a redemption date shall be made to the holder of such 2048 Notes on the record date related to such interest payment date. The redemption price will be calculated on the basis of a 360-day year consisting of twelve 30-day months. Calculation of the redemption price will be made by the issuer or on its behalf by such person as it will designate. Such calculation or the correctness thereof will not be a duty or obligation of the indenture trustee.

On and after the date of redemption, interest will cease to accrue on the 2048 Notes or portion of the 2048 Notes redeemed. However, interest will continue to accrue if the issuer defaults in the payment of the amount due upon redemption.

“Adjusted Treasury Rate” means, with respect to any redemption date, the rate per annum equal to the semi-annual equivalent yield to maturity of the Comparable Treasury Issue, assuming a price for the Comparable Treasury Issue (expressed as a percentage of its principal amount) equal to the Comparable Treasury Price for such redemption date.

“Comparable Treasury Issue” means the U.S. Treasury security selected by the Reference Treasury Dealer as having a maturity comparable to the remaining term of the 2028 Notes or the 2048 Notes, as applicable, to be

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redeemed, calculated as if the maturity date of the 2028 Notes was June 1, 2028 and the maturity date of the 2048 Notes was March 1, 2048, as applicable (the “Remaining Life”), that would be utilized, at the time of selection and in accordance with customary financial practice, in pricing new issues of corporate debt securities of comparable maturity to the applicable Remaining Life.

“Comparable Treasury Price” means, with respect to any redemption date, (A) the average of the Reference Treasury Dealer Quotations for such redemption date, after excluding the highest and lowest of such Reference Treasury Dealer Quotations, or (B) if the issuer obtains fewer than four such Reference Treasury Dealer Quotations, the average of all such quotations, or (C) if only one Reference Treasury Dealer Quotation is received, such quotation.

“Reference Treasury Dealer” means (A) each of Mizuho Securities USA LLC, RBC Capital Markets, LLC and TD Securities (USA) LLC, or their respective affiliates which are primary U.S. Government securities dealers in the United States (a “Primary Treasury Dealer”), and a Primary Treasury Dealer selected by MUFG Securities Americas Inc., and its successors; provided, however, that if any of the foregoing shall cease to be a Primary Treasury Dealer, the Company shall substitute therefor another Primary Treasury Dealer; and (B) any other Primary Treasury Dealer(s) selected by the Company.

“Reference Treasury Dealer Quotations” means, with respect to each Reference Treasury Dealer and any redemption date, the average, as determined by the issuer, of the bid and asked prices for the Comparable Treasury Issue (expressed in each case as a percentage of its principal amount) quoted in writing to the issuer by such Reference Treasury Dealer at 5:00 p.m. (New York City time) on the third business day preceding such redemption date.

Selection and Notice

If less than all of the notes of a series are to be redeemed in connection with any redemption, the indenture trustee will select notes (or portions of notes) of such series for redemption as follows:

The unredeemed portion of the principal amount of any note shall be in a denomination of at least $1,000 or integral multiples of $1,000. As long as the notes are represented by global notes registered in the name of DTC, or its nominee, beneficial interests in such global notes will be selected for redemption by DTC in accordance with its standard procedures therefor.

Notices of redemption will be mailed by first class mail and otherwise delivered in accordance with the applicable procedures of DTC at least 30 but not more than 60 days before the redemption date to each holder of notes to be redeemed at its registered address, except that redemption notices may be sent more than 60 days prior to a redemption date if the notice is issued in connection with a satisfaction and discharge of the indenture. Notices of redemption may not be conditional.

If any note is to be redeemed in part only, the notice of redemption that relates to that note will state the portion of the principal amount of that note that is to be redeemed. A new note in principal amount equal to the unredeemed portion of the original note will be issued in the name of the holder of notes upon cancellation of the original note (or through book-entry transfer). The notes called for redemption become due on the date fixed for redemption. On and after the redemption date, interest will cease to accrue on notes or portions of them called for redemption. However, interest will continue to accrue if the issuer defaults in the payment of the amount due upon redemption.

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Assumption

American Water may directly assume the due and punctual payment of the principal of (premium, if any) and interest on all the notes and the performance of every covenant of the indenture on the part of the issuer to be performed or observed. Upon any such assumption, American Water will succeed to and be substituted for and may exercise every right and power of the issuer under the indenture with the same effect as if it had been named as the issuer in the indenture and the issuer will be released from its liability as obligor on the notes. No such assumption shall be permitted unless American Water has delivered to the indenture trustee an officers’ certificate of American Water and an opinion of counsel for American Water, each stating that such assumption and supplemental indenture comply with this covenant and that all conditions precedent in the indenture relating to such transaction have been complied with.

Book-Entry Only Issuance

The notes will trade through DTC. The notes will be represented by one or more global certificates and registered in the name of Cede & Co., DTC’s nominee. Upon issuance of the notes, DTC or its nominee will credit, on its book-entry registration and transfer system, the principal amount of the notes represented by such global securities to the accounts of institutions that have an account with DTC or its participants. The accounts to be credited shall be designated by the underwriters. Ownership of beneficial interests in the global securities will be limited to participants or persons that may hold interests through participants. The global certificates will be deposited with the indenture trustee as custodian for DTC.

Holders of notes may elect to hold interests in a global security through DTC, Clearstream Banking, société anonyme (“Clearstream, Luxembourg”), or Euroclear Bank S.A./N.V., as operator of the Euroclear System (“Euroclear”), directly if they are participants in such systems, or indirectly through organizations which are participants in such systems.

Clearstream, Luxembourg and Euroclear will hold interests on behalf of their participants through customers’ securities accounts in Clearstream, Luxembourg’s and Euroclear’s names on the books of their respective depositaries, which in turn will hold such interests in customers’ securities accounts in the depositaries’ names on DTC’s books.

For a description of DTC and its book-entry system, see “Description of AWCC Debt Securities and American Water Support Agreement—Book-Entry, Delivery and Form—Depository Procedures” in the accompanying prospectus.

Purchases of global securities under the DTC system must be made by or through direct participants, which will receive a credit for the global securities on DTC’s records. The ownership interest of each actual purchaser of each security (“Beneficial Owner”) is in turn to be recorded on the direct and indirect participants’ records and Clearstream, Luxembourg and Euroclear will credit on their book-entry registration and transfer systems the number of notes sold to certain non-U.S. persons to the account of institutions that have accounts with Euroclear, Clearstream, Luxembourg or their respective nominee participants. Beneficial Owners will not receive written confirmation from DTC of their purchase, but Beneficial Owners are expected to receive written confirmations providing details of the transaction, as well as periodic statements of their holdings, from the direct participant or indirect participant through which the Beneficial Owner entered into the transaction.

Title to book-entry interests in the notes will pass by book-entry registration of the transfer within the records of Clearstream, Luxembourg, Euroclear or DTC, as the case may be, in accordance with their respective procedures. Book-entry interests in the notes may be transferred within Clearstream, Luxembourg and within Euroclear and between Clearstream, Luxembourg and Euroclear in accordance with procedures established for these purposes by Clearstream, Luxembourg and Euroclear. Book-entry interests in the notes may be transferred within DTC in accordance with procedures established for this purpose by DTC. Transfers of book-entry interests in the notes among Clearstream, Luxembourg, Euroclear and DTC may be effected in accordance with procedures established for this purpose by Clearstream, Luxembourg, Euroclear and DTC.

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Cross-market transfers between persons holding directly or indirectly through DTC on the one hand, and directly or indirectly through Clearstream, Luxembourg participants or Euroclear participants, on the other, will be effected through DTC in accordance with DTC’s rules; however, such cross-market transactions will require delivery of instructions to the relevant European international clearing system by the counterparty in such system in accordance with its rules and procedures and within the established deadlines of such system.

Due to time-zone differences, credits of the notes received in Clearstream, Luxembourg or Euroclear as a result of a transaction with a DTC participant will be made during subsequent securities settlement processing and dated the business day following the DTC settlement date. Such credits or any transactions in such notes settled during such processing will be reported to the relevant Clearstream, Luxembourg participant or Euroclear participant on such business day. Cash received in Clearstream, Luxembourg or Euroclear as a result of sales of the notes by or through a Clearstream, Luxembourg participant or a Euroclear participant to a DTC participant will be received with value on the DTC settlement date, but will be available in the relevant Clearstream, Luxembourg or Euroclear cash account only as of the business day following settlement in DTC.

Although DTC, Clearstream, Luxembourg and Euroclear have agreed to the foregoing procedures in order to facilitate transfers of the notes among participants of DTC, Clearstream, Luxembourg and Euroclear, they are under no obligation to perform or continue to perform such procedures and such procedures may be changed or discontinued at any time.

The information in this section and in the accompanying prospectus under “Description of AWCC Debt Securities and American Water Support Agreement—Book-Entry, Delivery and Form” concerning DTC and DTC’s book-entry system, Clearstream, Luxembourg and Euroclear has been obtained from sources that the issuer and the support provider believe to be reliable, but none of the issuer, the support provider or the underwriters take any responsibility for the accuracy of this information.

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CERTAIN UNITED STATES FEDERAL INCOME TAX CONSIDERATIONS

The following discussion is a summary of certain U.S. federal income tax consequences relevant to the purchase, ownership and disposition of the notes by the beneficial owners thereof, which are referred to as Holders. This discussion is limited to the tax consequences to the initial Holders of notes who purchase the notes at the initial offering price and does not address the tax consequences to subsequent purchasers of notes. This summary does not purport to be a complete analysis of all of the potential U.S. federal income tax consequences relating to the purchase, ownership and disposition of the notes, nor does this summary describe any federal estate tax consequences. There can be no assurance that the Internal Revenue Service (the “IRS”) will take a similar view of the tax consequences described herein. Furthermore, this discussion does not address all aspects of taxation that might be relevant to particular purchasers in light of their individual circumstances. For instance, this discussion does not address the alternative minimum tax provisions of the Code (as defined below) or special rules applicable to certain categories of purchasers (including dealers in securities or foreign currencies, traders in securities that elect to use a mark-to-market method of accounting for the securities holdings, insurance companies, real estate investment trusts, regulated investment companies, financial institutions, tax-exempt entities, persons required to report income with respect to a note no later than such income is reported on an “applicable financial statement” under Section 451 of the Internal Revenue Code of 1986, as amended (the “Code”), U.S. Holders (as defined below) whose functional currency is not the U.S. dollar and, except to the extent discussed below, Non-U.S. Holders (as defined below)) or to purchasers who acquire or sell the notes as part of a wash sale for tax purposes or hold the notes as part of a hedge, straddle, conversion or constructive sale transaction or other risk reduction transaction.

This discussion is based on the provisions of the Code, the Treasury Regulations promulgated thereunder, and administrative and judicial interpretations thereof, all as in effect as of the date hereof and all of which are subject to change (possibly with retroactive effect). The discussion below assumes that Holders hold the notes as capital assets within the meaning of Section 1221 of the Code.

If a partnership, or an entity treated as a partnership for U.S. federal income tax purposes, holds any notes, the tax treatment of such entity and each partner will generally depend on the status of the partner and the activities of the partnership. Partnerships and their partners should consult their tax advisors regarding the tax consequences of owning the notes.

Prospective holders are urged to consult their tax advisors as to the specific tax consequences of a purchase of the notes in light of their particular tax situation, including the application and effect of the Code, as well as state, local and foreign income and other tax laws.

Tax Consequences to U.S. Holders

The following summary is a general description of certain U.S. federal income tax consequences applicable to a “U.S. Holder.” For the purpose of this discussion, “U.S. Holder” means a Holder of a note that is for U.S. federal income tax purposes (i) a citizen or resident of the United States, (ii) a corporation, or other entity treated as a corporation for U.S. federal income tax purposes, created or organized in or under the laws of the United States or of any political subdivision thereof (including the District of Columbia), (iii) an estate, the income of which is subject to U.S. federal income taxation regardless of its source, or (iv) a trust, if (A) the administration of the trust is subject to the primary supervision of a court within the United States and one or more U.S. persons has the authority to control all substantial decisions of the trust, or (B) has a valid election in place under applicable U.S. Treasury Regulations to be treated as a U.S. person.

As described above in “Description of the Notes—Optional Redemption by the Issuer,” the issuer may make payments upon a redemption in excess of the principal amount of the notes. Under applicable Treasury Regulations, because the issuer would minimize the yield on the notes by not exercising this redemption option, such payments should not be accounted for in making a determination of whether the notes should be treated as

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contingent payment debt instruments for U.S. federal income tax purposes. Given the issuer’s determination, the issuer does not intend to treat the notes as contingent payment debt instruments for U.S. federal income tax purposes. If the IRS or a court were to take a contrary position, the notes could be subject to U.S. federal income tax rules governing contingent payment debt instruments, in which case the amount and timing of income inclusions with respect to the notes and the character of income recognized on a sale, exchange or redemption of a note, could differ materially and adversely from what is described below. The remainder of this discussion assumes that the notes will not be subject to the contingent payment debt instrument rules. This assumption is made solely for U.S. federal income tax purposes and is not an indication of the issuer’s intention to call or not to call the notes at any time.

Payments of Stated Interest

Generally, stated interest paid on a note will be taxable to a U.S. Holder as ordinary interest income at the time the interest accrues or is received in accordance with the U.S. Holder’s method of accounting for U.S. federal income tax purposes.

Sale, Exchange, Redemption or Retirement of the Notes

In general, upon the sale, exchange, redemption or retirement of a note, a U.S. Holder will recognize capital gain or loss equal to the difference between the amount realized on such sale, exchange, redemption, retirement (not including any amount attributable to accrued but unpaid interest) and such U.S. Holder’s adjusted tax basis in the note. To the extent attributable to accrued but unpaid interest, the amount recognized by the U.S. Holder will be treated as a payment of interest. See “—Payments of Stated Interest” above. A U.S. Holder’s adjusted tax basis in a note generally will equal the cost of the note to such U.S. Holder. The capital gain or loss will be long-term if a U.S. Holder’s holding period is more than one year at the time of sale, exchange, redemption, retirement or other disposition and will be short-term if a U.S. Holder’s holding period is one year or less. Long-term capital gains of individuals are generally eligible for reduced rates of taxation. The deductibility of capital losses is subject to limitations.

The assumption described above in “Description of the Notes—Assumption” may be treated as a “deemed exchange” of a note for a new note of the assuming corporation for U.S. federal income tax purposes. If the assumption is treated as a deemed exchange, then the consequences in the preceding paragraph would apply. Prospective Holders are urged to consult their tax advisors regarding the tax consequences of such an assumption.

Under certain circumstances described in “Description of AWCC Debt Securities and American Water Support Agreement—Discharge” in the accompanying prospectus, the issuer will be discharged from any and all obligations in respect of the notes. Such discharge may be treated as a taxable exchange for U.S. federal income tax purposes. U.S. Holders should consult their own tax advisors regarding the U.S. federal, state, and local tax consequences of such a discharge.

Medicare Tax

A U.S. Holder that is an individual or estate, or a trust that does not fall into a special class of trusts that is exempt from such tax, will be subject to a 3.8% tax on the lesser of (1) the U.S. Holder’s “net investment income” (or “undistributed net investment income,” in the case of an estate or trust) for the relevant taxable year and (2) the excess of the U.S. Holder’s modified adjusted gross income for the taxable year over a certain threshold (which in the case of individuals will be between $125,000 and $250,000, depending on the individual’s circumstances). A U.S. Holder’s net investment income will generally include its interest income and its net gains from the disposition of notes, unless such interest income or net gains are derived in the ordinary course of the conduct of a trade or business (other than a trade or business that consists of certain passive or trading activities). U.S. Holders that are individuals, estates or trusts are urged to consult their tax advisors regarding the applicability of the Medicare tax to their income and gains in respect of their investment in the notes.

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Tax Consequences to Non-U.S. Holders

The following summary is a general description of certain U.S. federal income tax consequences to a “Non-U.S. Holder.” A “Non-U.S. Holder” means, for purposes of this discussion, a Holder (other than a partnership, or other entity treated as a partnership for U.S. federal income tax purposes) that is not a U.S. Holder. Special rules may apply to certain Non-U.S. Holders such as “controlled foreign corporations,” “passive foreign investment companies” and certain U.S. individuals that are expatriates and such Non-U.S. Holders should consult their tax advisors.

Stated Interest

Subject to the discussions below under “—Backup Withholding and Information Reporting” and “—Withholdable Payments to Foreign Financial Entities” and assuming that a Non-U.S. Holder’s interest income on a note is not effectively connected with the conduct by such Non-U.S. Holder of a trade or business in the United States, payments of interest on a note by the issuer or any paying agent to a Non-U.S. Holder will not be subject to U.S. federal income tax or withholding tax, provided that the Non-U.S. Holder:

Payments of interest on a note that do not satisfy all of the foregoing requirements are generally subject to U.S. federal income tax and withholding tax at a flat rate of 30% (or a lower applicable treaty rate, provided certain certification requirements are met).

Except to the extent otherwise provided under an applicable tax treaty, a Non-U.S. Holder generally will be subject to U.S. federal income tax in the same manner as a U.S. Holder with respect to interest that is effectively connected with a U.S. trade or business conducted by the Non-U.S. Holder. Effectively connected interest income received by a corporate Non-U.S. Holder may also, under certain circumstances, be subject to an additional “branch profits tax” at a 30% rate, or, if applicable, a lower treaty rate. Such effectively connected interest income will not be subject to withholding tax if the Non-U.S. Holder delivers an IRS Form W-8ECI to the payor.

Under Code Sections 871(h) and 881(c) and the underlying U.S. Treasury Regulations, in order to obtain the exemption from withholding tax described above, the Non-U.S. Holder of a note must provide its name and address, and certify, under penalties of perjury, to AWCC or the paying agent, as the case may be, that such Holder is a Non-U.S. Holder. Such certification may be made on IRS Form W-8BEN or W-8BEN-E as applicable. In general, a certificate described in this paragraph is effective only with respect to payments of interest made to the certifying Non-U.S. Holder after issuance of the certificate in the calendar year of its issuance and the three immediately succeeding calendar years (or, if earlier, until a change in circumstances makes any of the information in the form incorrect).

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Repayment of Principal and Realized Gain

Subject to the discussions below under “—Backup Withholding and Information Reporting” and “—Withholdable Payments to Foreign Financial Entities,” a Non-U.S. Holder of a note will not be subject to U.S. federal withholding tax on the receipt of payments of principal on the note, and a Non-U.S. Holder will not be subject to U.S. federal income tax on any gain realized on the sale, exchange, redemption, retirement or other disposition of such note (other than amounts attributable to accrued but unpaid interest, which will be treated as described under “—Tax Consequences to Non-U.S. Holders—Stated Interest” above), or receipt of principal, unless:

Backup Withholding and Information Reporting

Under current U.S. federal income tax law, backup withholding and information reporting requirements apply to certain payments of principal and interest made to, and to the proceeds of sale before maturity by, certain U.S. Holders.

In the case of a non-corporate U.S. Holder, information reporting requirements will apply to payments of principal or interest made by the issuer or any paying agent thereof on a note. The payor will be required to withhold backup withholding tax at the current rate of 24% with respect to certain “reportable payments,” including interest on or principal (and premium, if any) of a note and the gross proceeds from a disposition of a note if:

Backup withholding and information reporting do not apply with respect to payments made to certain exempt recipients, which currently include entities treated as corporations for U.S. federal income tax purposes provided their exemptions from backup withholding are properly established.

In the case of a Non-U.S. Holder, under currently applicable Treasury Regulations, backup withholding and information reporting will not apply to payments of principal or interest made by the issuer or any paying agent thereof on a note (absent actual knowledge or reason to know that the Holder is actually a U.S. Holder) if such Non-U.S. Holder has provided the required certification under penalties of perjury that it is not a U.S. Holder or has otherwise established an exemption. However, the issuer and other payors are required to report payments of interest on a Non-U.S. Holder’s notes on IRS Form 1042-S even if the payments are not otherwise subject to information reporting requirements. If such Holder provides the required certification, such Holder may nevertheless be subject to withholding of U.S. federal income tax as described above under “—Tax Consequences to Non-U.S. Holders—Stated Interest.” The rules regarding withholding, backup withholding and

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information reporting for Non-U.S. Holders are complex, may vary depending on a Non-U.S. Holder’s particular situation and are subject to change. In addition, special rules apply to certain types of Non-U.S. Holders, including partnerships, trusts and other entities treated as pass-through entities for U.S. federal income tax purposes. Non-U.S. Holders of notes should accordingly consult their tax advisors regarding the application of information reporting and backup withholding in their particular situations, the availability of an exemption therefrom, and the procedure for obtaining such an exemption if applicable.

Backup withholding is not an additional tax; any amounts withheld from a payment to a Holder under the backup withholding rules will be allowed as a credit against such Holder’s U.S. federal income tax liability and may entitle such Holder to a refund, provided that certain required information is furnished to the IRS.

Withholdable Payments to Foreign Financial Entities

Under the Foreign Account Tax Compliance Act (“FATCA”), the issuer and/or other payors generally will be required to withhold 30% of any interest on the notes, and, effective January 1, 2019, 30% of the gross proceeds from a sale, exchange, redemption or retirement of the notes, paid (i) to a foreign financial institution unless such foreign financial institution agrees to verify, report and disclose its U.S. accountholders and meets certain other requirements, or (ii) to a non-financial foreign entity unless such entity certifies that it does not have any substantial United States owners or provides the name, address and taxpayer identification number of each substantial United States owner and meets certain other requirements. Foreign financial institutions located in jurisdictions that have intergovernmental agreements with the United States may be subject to different rules. If payment of this withholding tax is made, Non-U.S. Holders that are otherwise eligible for an exemption from, or reduction of, U.S. federal withholding taxes with respect to such interest or proceeds will be required to seek a credit or refund from the IRS to obtain the benefit of such exemption or reduction. You should consult your tax advisor regarding the potential application of these withholding rules to your investment in the notes.

The U.S. federal income tax discussion set forth above is included for general information only and may not be applicable depending upon a holder’s particular situation. Holders should consult their tax advisors regarding the tax consequences to them of the purchase, ownership and disposition of notes, including the tax consequences under state, local, foreign and other tax laws.

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UNDERWRITING (CONFLICTS OF INTEREST)

Subject to the terms and conditions set forth in an underwriting agreement dated the date of this prospectus supplement between the issuer, American Water and the underwriters named below, the issuer has agreed to sell to each of the underwriters, and each of the underwriters has severally agreed to purchase from the issuer, the principal amount of notes set forth opposite its name below:

The offering of the notes by the underwriters is subject to receipt and acceptance and subject to the underwriters’ right to reject any order in whole or in part. The underwriting agreement provides that the underwriters are obligated to purchase all of the notes in the offering if any are purchased.

The underwriters have advised the issuer and American Water that they propose initially to offer each series of notes at the price to public set forth on the cover of this prospectus supplement with respect to such series, and to certain dealers at such price less a concession not in excess of     % of the principal amount of the 2028 Notes and of     % of the principal amount of the 2048 Notes. The underwriters may allow, and such dealers may reallow, a concession not in excess of     % of the principal amount of the 2028 Notes and of     % of the principal amount of the 2048 Notes to certain other dealers. If all of a series of notes are not sold at the price to public of such series of notes set forth on the cover page of this prospectus supplement, the offering price and other selling terms for such series of notes may be changed by the underwriters.

American Water estimates that the total expenses of the offering, including registration, printing fees and legal and accounting expenses but excluding underwriting discounts, will be approximately $2,350,000.

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The issuer and the support provider have agreed to indemnify the underwriters against liabilities relating to this offering, including liabilities under the Securities Act, or contribute to payments that the underwriters may be required to make in that respect.

The notes are each a new issue of securities with no established trading market. The issuer does not intend to apply for listing of the notes on any securities exchange or on any automated dealer quotation system. American Water and the issuer have been advised by the underwriters that they presently intend to make a market in the notes as permitted by applicable laws and regulations. The underwriters are not obligated, however, to make a market in the notes and any such market making may be discontinued without notice at any time at the sole discretion of the underwriters. Accordingly, no assurance can be given as to the liquidity of, or trading market for, the notes.

In connection with the offering, the underwriters may engage in stabilizing transactions, over-allotment transactions, covering transactions and penalty bids in accordance with Regulation M under the Exchange Act.

These stabilizing transactions, covering transactions and penalty bids may have the effect of raising or maintaining the market price of the notes or preventing or retarding a decline in the market price of the notes. As a result, the price of the notes may be higher than the price that might otherwise exist in the open market. These transactions may be discontinued at any time without notice.

Conflicts of Interest

The underwriters and their affiliates have engaged, and may in the future engage, in transactions with, and from time to time have performed services for, the issuer, the support provider and the support provider’s affiliates in the ordinary course of business, for which they have received and will receive customary compensation. Affiliates of certain of the underwriters are also lenders under the issuer’s primary revolving credit facility and dealers under the issuer’s commercial paper program.

Certain of the underwriters or their affiliates may hold a portion of the long-term debt or commercial paper that the issuer intends to repay using the net proceeds from this offering. In such event, it is possible that one or more of the underwriters or their affiliates could receive at least 5% of the net proceeds from the offering, and in that case such underwriter would be deemed to have a conflict of interest under FINRA Rule 5121. In the event of any such conflict of interest, such underwriter would be required to conduct the distribution of the notes in accordance with FINRA Rule 5121. If the distribution is conducted in accordance with FINRA Rule 5121, such underwriter would not be permitted to confirm a sale to an account over which it exercises discretionary authority without first receiving specific written approval from the account holder.

In addition, in the ordinary course of their business activities, the underwriters and their affiliates may make or hold a broad array of investments and actively trade debt and equity securities (or related derivative securities) and financial instruments (including bank loans) for their own account and for the accounts of their customers. Such investments and securities activities may involve securities and/or instruments of the issuer, the support provider or the support provider’s affiliates. If any of the underwriters or their affiliates have a lending

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relationship with the issuer, the support provider or the support provider’s affiliates, certain of those underwriters or their affiliates routinely hedge, and certain other of those underwriters may hedge, their credit exposure to the issuer, the support provider or the support provider’s affiliates consistent with their customary risk management policies. Typically, these underwriters and their affiliates would hedge such exposure by entering into transactions which consist of either the purchase of credit default swaps or the creation of short positions in securities of the issuer, the support provider or the support provider’s affiliates, including potentially the notes offered hereby. Any such credit default swaps or short positions could adversely affect future trading prices of the notes offered hereby. The underwriters and their affiliates may also make investment recommendations and/or publish or express independent research views in respect of such securities or financial instruments and may hold, or recommend to clients that they acquire, long and/or short positions in such securities and instruments.

Trustee Conflict of Interest

Wells Fargo Securities, LLC, an affiliate of the trustee, is an underwriter for this offering. Therefore, if a default occurs with respect to the notes, the trustee would have a conflicting interest for purposes of the Trust Indenture Act of 1939. In that event, except in very limited circumstances, the trustee would be required to resign as trustee under the indenture under which the notes are being issued and we would be required to appoint a successor trustee. If the trustee resigns following a default, it may be difficult to identify and appoint a qualified successor trustee.

Selling Restrictions

Canada

The notes may be sold in Canada only to purchasers purchasing, or deemed to be purchasing, as principal that are accredited investors, as defined in National Instrument 45-106 Prospectus Exemptions or subsection 73.3(1) of the Securities Act (Ontario), and are permitted clients, as defined in National Instrument 31-103 Registration Requirements, Exemptions and Ongoing Registrant Obligations. Any resale of the notes must be made in accordance with an exemption from, or in a transaction not subject to, the prospectus requirements of applicable securities laws.

Securities legislation in certain provinces or territories of Canada may provide a purchaser with remedies for rescission or damages if this prospectus supplement (including any amendment thereto) contains a misrepresentation, provided that the remedies for rescission or damages are exercised by the purchaser within the time limit prescribed by the securities legislation of the purchaser’s province or territory. The purchaser should refer to any applicable provisions of the securities legislation of the purchaser’s province or territory for particulars of these rights or consult with a legal advisor.

Pursuant to section 3A.3 of National Instrument 33-105 Underwriting Conflicts (“NI 33-105”), the underwriters are not required to comply with the disclosure requirements of NI 33-105 regarding underwriter conflicts of interest in connection with this offering.

PRIIPs Regulation/Prospectus Directive/Prohibition of Sales to EEA Retail Investors

The notes are not intended to be offered, sold or otherwise made available to and should not be offered, sold or otherwise made available to any retail investor in the European Economic Area (“EEA”). For these purposes, a retail investor means a person who is one (or more) or: (i) a retail client as defined in point (11) of Article 4(1) of Directive 2014/65/EU (as amended, “MiFID II”); (ii) a customer within the meaning of Directive 2002/92/EC, as amended, where that customer would not qualify as a professional client as defined in point (10) of Article 4(1) of MiFID II; or (iii) not a qualified investor as defined in Directive 2003/71/EC (as amended, the “Prospectus Directive”). Consequently no key information document required by Regulation (EU) No 1286/2014 (as amended, the “PRIIPs Regulation”) for offering or selling the notes or otherwise making them available to any

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retail investor in the EEA has been prepared and therefore offering or selling the notes or otherwise making them available to any retail investor in the EEA may be unlawful under the PRIIPs Regulation. This prospectus supplement and the accompanying prospectus have been prepared on the basis that any offer of notes in any member state of the EEA will be made pursuant to an exemption under the Prospectus Directive from the requirements to publish a prospectus for offers of the notes. This prospectus supplement and the accompanying prospectus is not a prospectus for purposes of the Prospectus Directive as implemented in member states of the EEA.

Hong Kong

The notes have not been and may not be offered or sold in Hong Kong by means of any document (except for notes which are “structured product” as defined in the Securities and Futures Ordinance (Cap. 571, the Laws of Hong Kong) (the “Securities and Futures Ordinance”)) other than (i) to “professional investors” as defined in the Securities and Futures Ordinance and any rules made thereunder, or (ii) in other circumstances which do not result in the document being a “prospectus” as defined in the Companies (Winding Up and Miscellaneous Provisions) Ordinance (Cap. 32, the Laws of Hong Kong) (the “C(WUMP)O”) or which do not constitute an offer to the public within the meaning of the C(WUMP)O. No advertisement, invitation or document relating to the notes has been or may be issued or has been or may be in the possession of any person for the purpose of issue (in each case whether in Hong Kong or elsewhere), which is directed at, or the contents of which are likely to be accessed or read by, the public in Hong Kong (except if permitted to do so under the securities laws of Hong Kong) other than with respect to notes which are or are intended to be disposed of only to persons outside Hong Kong or only to “professional investors” as defined in the Securities and Futures Ordinance and any rules made thereunder.

Japan

The notes have not been and will not be registered under the Financial Instruments and Exchange Act of Japan (Act No. 25 of 1948, as amended), or the FIEA. The notes may not be offered or sold, directly or indirectly, in Japan or to or for the benefit of any resident of Japan (including any person resident in Japan or any corporation or other entity organized under the laws of Japan) or to others for reoffering or resale, directly or indirectly, in Japan or to or for the benefit of any resident of Japan, except pursuant to an exemption from the registration requirements of, and otherwise in compliance with, the FIEA and any other applicable laws, regulations and ministerial guidelines of Japan.

Singapore

Neither this prospectus supplement nor the accompanying prospectus has been registered as a prospectus with the Monetary Authority of Singapore. Accordingly, this prospectus supplement, the accompanying prospectus and any other document or material in connection with the offer or sale, or invitation for subscription or purchase, of the notes may not be circulated or distributed, nor may the notes be offered or sold, or be made the subject of an invitation for subscription or purchase, whether directly or indirectly, to persons in Singapore other than (i) to an institutional investor (as defined in Section 4A of the Securities and Futures Act, Chapter 289 of Singapore (the “SFA”) pursuant to Section 274 of the SFA, (ii) to a relevant person (as defined in Section 275(2) of the SFA) pursuant to Section 275(1) of the SFA, or any person pursuant to Section 275(1A) of the SFA, and in accordance with the conditions specified in Section 275 of the SFA or (iii) otherwise pursuant to, and in accordance with the conditions of, any other applicable provision of the SFA.

Where the notes are subscribed or purchased under Section 275 of the SFA by a relevant person which is (a) a corporation (which is not an accredited investor (as defined in Section 4A of the SFA)) the sole business of which is to hold investments and the entire share capital of which is owned by one or more individuals, each of whom is an accredited investor, or (b) a trust (where the trustee is not an accredited investor ) whose sole purpose is to hold investments and each beneficiary of the trust is an accredited investor, the securities (as defined in

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Section 239(1) of the SFA) of that corporation or the beneficiaries’ rights and interest (howsoever described) in that trust shall not be transferred within six months after that corporation or that trust has subscribed or purchased the notes under an offer made pursuant to Section 275 of the SFA except: (1) to an institutional investor pursuant to Section 274 of the SFA or to a relevant person (as defined in Section 275(2) of the SFA), or to any person arising from an offer referred to in Section 275(1A) or Section 276(4)(i)(B) of the SFA, (2) where no consideration is or will be given for the transfer, (3) where the transfer is by operation of law, (4) as specified in Section 276(7) of the SFA, or (5) as specified in Regulation 32 of the Securities and Futures (Offers of Investments) (Shares and Debentures) Regulations 2005 of Singapore.

Switzerland

The notes may not be publicly offered, sold or advertised, directly or indirectly, in or from Switzerland, and will not be listed on the SIX Swiss Exchange Ltd or any other exchange or regulated trading venue in Switzerland. Neither this prospectus supplement and the accompanying prospectus, nor any other offering or marketing material relating to the notes constitutes a prospectus as such term is understood pursuant to article 652a or article 1156 of the Swiss Federal Code of Obligations or a listing prospectus within the meaning of the listing rules of the SIX Swiss Exchange Ltd or any other exchange or regulated trading venue in Switzerland, and neither this prospectus nor any other offering or marketing material relating to the notes may be publicly distributed or otherwise made publicly available in Switzerland.

United Kingdom

This prospectus supplement and the accompanying prospectus are only being distributed to and are only directed at (i) persons who are outside the United Kingdom or (ii) investment professionals falling within Article 19(5) of the Financial Services and Markets Act 2000 (Financial Promotion) Order 2005 (the “Order”) or (iii) high net worth entities, and other persons to whom it may lawfully be communicated, falling within Article 49(2)(a) to (d) of the Order (all such persons together being referred to as “relevant persons”). This document must not be acted on or relied on in the United Kingdom by persons who are not relevant persons. In the United Kingdom, any notes will only be available to, and any invitation, offer or agreement to subscribe, purchase or otherwise acquire such notes will be engaged in only with, relevant persons.

Each underwriter

LEGAL MATTERS

Certain legal matters in connection with this offering, including the validity of the notes, will be passed upon for AWCC and American Water by Morgan, Lewis & Bockius LLP, New York, New York. Certain legal matters in connection with this offering will be passed upon for AWCC and American Water by Jeffrey M. Taylor, Secretary of AWCC and Chief SEC & Corporate Governance Counsel and Assistant Secretary of American Water. The validity of the notes will be passed upon for the underwriters by Sullivan & Cromwell LLP, New York, New York. As of August 6, 2018, Mr. Taylor owned 297 shares of American Water’s common stock, 2,033 performance stock units, none of which are earned, 572 unvested restricted stock units and options to purchase 2,185 shares of its common stock, of which options to purchase 1,456 shares are vested.

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American Water Works Company, Inc.

Common Stock

Preferred Stock

Support Agreement

Depositary Shares

Stock Purchase Contracts

Stock Purchase Units

Subscription Rights

Warrants

American Water Capital Corp.

Debt Securities

The securities covered by this prospectus may be sold by American Water Works Company, Inc., or American Water, from time to time, independently or together with American Water Capital Corp., or AWCC, a wholly-owned subsidiary of American Water Works Company, Inc. Any debt securities issued by AWCC will have the benefit of a support agreement from American Water. In addition, selling security holders who may be named in a prospectus supplement may offer and sell from time to time securities in such amounts as set forth in such prospectus supplement. We may, and any selling security holder may, offer the securities independently or together in any combination for sale directly to purchasers or through underwriters, dealers or agents to be designated at a future date. We may, and any selling security holder may, offer and sell these securities in amounts, at prices and on terms determined at the time of the offering. Unless otherwise set forth in a prospectus supplement, we will not receive any proceeds from the sale of securities by any selling security holders.

When we offer securities, a prospectus supplement will describe the specific terms of the specific issue of securities. Prospectus supplements may also add, update or change the information in this prospectus. You should carefully read this prospectus and the prospectus supplement relating to the specific issue of securities, together with the documents we incorporate by reference, before you decide to invest in any of these securities.

American Water Works Company, Inc. common stock is listed on the New York Stock Exchange under the symbol “AWK.” The mailing address of our principal executive offices is 1025 Laurel Oak Road, Voorhees, New Jersey 08043, and our telephone number is (856) 346-8200.

Investing in these securities involves certain risks. See “Risk Factors” on page i of this prospectus. You should carefully review the risks and uncertainties described under the heading “Risk Factors” contained in this prospectus and any risk factors set forth in each applicable prospectus supplement and any related free writing prospectus, and under similar headings in the other documents that are incorporated by reference into this prospectus.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or passed upon the adequacy or accuracy of this prospectus. Any representation to the contrary is a criminal offense.

The securities may be offered and sold to or through underwriters, dealers, agents or other third parties as designated from time to time, or directly to one or more other purchasers or through a combination of such methods on a continuous or delayed basis. See “Plan of Distribution” on page 30. If any underwriters, dealers or agents are involved in the sale of any of the securities, their names, and any applicable purchase price, fee, commission or discount arrangements between or among them, will be set forth, or will be calculable from the information set forth, in the applicable prospectus supplement.

The date of this prospectus is May 1, 2018.

RISK FACTORS

An investment in our securities involves risk. Before you invest in securities issued by us, you should carefully consider the risks involved. Accordingly, you should carefully consider:

The discussion of risks related to our business contained in or incorporated by reference into this prospectus or into any prospectus supplement comprises material risks of which we are aware. If any of the events or developments described actually occurs, our business, financial condition or results of operations would likely suffer.

You should also be aware that new risks may emerge in the future at any time, and we cannot predict such risks or estimate the extent to which they may affect our business, financial condition or results of operations. The prospectus supplement applicable to each type or series of securities we offer may contain a discussion of additional risks applicable to an investment in us and the particular type of securities we are offering under that prospectus supplement.

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TABLE OF CONTENTS

ABOUT THIS PROSPECTUS

This prospectus is part of a registration statement that American Water and AWCC filed with the Securities and Exchange Commission, or the SEC, using a “shelf” registration process. Under this shelf registration process, we, or certain of our security holders, may sell the securities described in this prospectus in one or more offerings from time to time. Each time we, or, under certain circumstances, our security holders, sell securities under this shelf registration, we will provide a prospectus supplement that will contain specific information about the terms of the offering. The prospectus supplement may also add to, modify or supersede the information contained in this prospectus. You should read both this prospectus and the applicable prospectus supplement together with the additional information referred to below under “Where You Can Find More Information.” If there is any inconsistency between the information in the prospectus and the prospectus supplement, you should rely on the information in the prospectus supplement.

The prospectus supplement will describe: the terms of the securities offered, any initial public offering price, any price paid to us for the securities, the net proceeds to us, if any, the manner of distribution and any underwriting compensation and the other specific material terms related to the offering of the applicable securities. For more detail on the terms of the securities, you should read the exhibits filed with or incorporated by reference in our registration statement of which this prospectus forms a part.

All references in this prospectus to “we,” “our” and “us” refer to American Water Works Company, Inc. and its consolidated subsidiaries unless the context otherwise requires. The term “American Water” refers to American Water Works Company, Inc. The term “AWCC” refers to American Water Capital Corp.

References to “securities” include any security that we or our security holders might sell under this prospectus or any prospectus supplement.

This prospectus contains summaries of certain provisions contained in some of the documents described herein. Please refer to the actual documents for complete information. All of the summaries are qualified in their entirety by reference to the actual documents. Copies of the documents referred to herein have been filed, or will be filed or incorporated by reference as exhibits to the registration statement of which this prospectus is a part, and you may obtain copies of those documents as described below under “Where You Can Find More Information.”

You should rely only on the information incorporated by reference into this prospectus or provided in this prospectus or any prospectus supplement or in any written communication from us specifying the final terms of a particular offering of securities. We have not authorized anyone to provide you with different information. The distribution of this prospectus and sale of these securities in certain jurisdictions may be restricted by law. You should inform yourself about and observe any such restrictions. We are not making an offer to sell these securities in any jurisdiction where the offer or sale is not permitted. You should assume that the information appearing in this prospectus is accurate as of the date on the front cover of this prospectus only and any information we have incorporated by reference is only accurate as of the date of the document incorporated by reference. Our business, financial condition, results of operations and prospects may have changed since that date.

FORWARD-LOOKING STATEMENTS

This prospectus and any prospectus supplement, the documents incorporated by reference or any other written or oral statements made by or on behalf of American Water or AWCC may include statements that reflect current views with respect to future events. These statements are “forward-looking statements” within the meaning of Section 27A of the Securities Act of 1933, as amended, or the Securities Act, Section 21E of the Securities Exchange Act of 1934, as amended, or the Exchange Act, and the Private Securities Litigation Reform

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Act of 1995. In some cases, these forward-looking statements can be identified by words with prospective meanings such as “intend,” “plan,” “estimate,” “believe,” “anticipate,” “expect,” “predict,” “project,” “propose,” “assume,” “forecast,” “likely,” “outlook,” “future,” “pending,” “goal,” “objective,” “potential,” “continue,” “seek to,” “may,” “can,” “should,” “will” and “could” or the negative of such terms or other variations or similar expressions. Forward-looking statements may relate to, among other things, future financial performance, including adjusted operation and maintenance, or O&M, efficiency ratio, cash flows, growth and portfolio optimization strategies; projected capital expenditures and related funding requirements; the ability to repay debt; the projected strategy to finance current operations and growth initiatives; the impact of legal proceedings and potential fines and penalties; business process and technology improvement initiatives; trends in the utility and water services industries; and regulatory, legislative, political, tax policy or legal developments or rate adjustments, including rate case filings, filings for infrastructure surcharges and filings to address regulatory lag.

Forward-looking statements are predictions based on our current expectations and assumptions regarding future events. They are not guarantees of any outcomes, financial results or levels of performance and you are cautioned not to place undue reliance upon them. These forward-looking statements are subject to a number of estimates and assumptions, and known and unknown risks, uncertainties and other factors. Our actual results may vary materially from those discussed in such forward-looking statements as a result of the following important factors:

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These forward-looking statements are qualified by, and should be read together with, the risk factors and other cautionary statements contained in our Annual Report on Form 10-K for the year ended December 31, 2017, and our other filings with the SEC, which are incorporated by reference into this prospectus, and you should refer to such risks, uncertainties and risk factors in evaluating such forward-looking statements. Any forward-looking statements we make speak only as of the date of the document in which they are contained. Except as required by the federal securities laws, we do not have any obligation, and we specifically disclaim any undertaking or intention, to publicly update or revise any forward-looking statements, whether as a result of new information, future events, changed circumstances or otherwise. New factors emerge from time to time, and it is not possible for us to predict all such factors. Furthermore, it may not be possible to assess the impact of any such factor on our businesses, either viewed independently or together, or the extent to which any factor, or combination of factors, may cause results to differ materially from those contained in any forward-looking statement. The foregoing factors should not be construed as exhaustive.

AMERICAN WATER WORKS COMPANY, INC.

We are the most geographically diversified, as well as the largest publicly-traded, U.S. water and wastewater utility company, as measured by both operating revenues and population served. As a holding company, we conduct substantially all of our business operations through our subsidiaries. We employ approximately 6,900 employees to provide an estimated 15 million people with drinking water, wastewater and other water-related services in 46 states, the District of Columbia and Ontario, Canada.

In 2017, American Water generated $3,357 million in total consolidated operating revenues and $426 million in net income attributable to common stockholders. In 2016, American Water generated $3,302 million in total consolidated operating revenues and $468 million in net income attributable to common stockholders.

American Water conducts its business primarily through its Regulated Businesses segment. American Water also operates businesses that provide a broad range of related and complementary water and wastewater services in non-regulated markets, which includes four operating segments that individually do not meet the criteria of a reportable segment in accordance with generally accepted accounting principles in the United States, which are collectively referred to in this prospectus as its Market-Based Businesses.

For 2017, American Water’s Regulated Businesses segment generated $2,958 million in operating revenues, prior to inter-segment eliminations, which accounted for 88.1% of American Water’s total consolidated operating revenues. For the same period, American Water’s Market-Based Businesses generated $422 million in operating revenues, prior to inter-segment eliminations, which accounted for 12.6% of total consolidated operating revenues.

American Water’s principal executive offices are located at 1025 Laurel Oak Road, Voorhees, New Jersey 08043, and its telephone number is (856) 346-8200.

AMERICAN WATER CAPITAL CORP.

American Water’s financing activities include the issuance of long-term and short-term debt, primarily through AWCC, its wholly owned finance subsidiary. AWCC loans all of the net proceeds of its long-term debt financings to American Water’s regulated operating subsidiaries, as well as to American Water. AWCC also provides liquidity to the Regulated Businesses segment and American Water through AWCC’s revolving credit facility and commercial paper program. All of AWCC’s long-term debt loaned to American Water’s Regulated Businesses segment or American Water is evidenced by promissory notes issued to AWCC by the regulated operating subsidiaries or American Water, as applicable. As of December 31, 2017, American Water had $7,725 million in total debt, including $6,498 million in long-term debt, of which the current portion is $322 million , and $905 million in short-term commercial paper borrowings at AWCC.

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AWCC’s principal executive offices are located at 1025 Laurel Oak Road, Voorhees, New Jersey 08043, and its telephone number is (856) 346-8200.

USE OF PROCEEDS

Unless we inform you otherwise in a prospectus supplement or free writing prospectus, the net proceeds from the sale of AWCC Debt Securities will be used to repay certain of our outstanding indebtedness or loaned to American Water and/or its regulated operating subsidiaries, and American Water and/or its regulated operating subsidiaries intend to use the proceeds of such loans, and the net proceeds from the sale of securities issued by American Water, for the following purposes:

Unless otherwise set forth in a prospectus supplement, we will not receive any proceeds from any sales of our securities by any selling security holder who may be named in a prospectus supplement.

RATIO OF EARNINGS TO FIXED CHARGES

For purposes of calculating the ratio of earnings to fixed charges, earnings consists of income (loss) from continuing operations before income taxes including the effect of allowance for funds used during construction, which we refer to as AFUDC, plus fixed charges. Fixed charges consist of interest expense, amortization of debt issuance costs, and a portion of rent expense that management believes is representative of the interest component of rental expense. Fixed charges have not been reduced for the effect of AFUDC. In addition, neither American Water nor AWCC had any preferred stock outstanding for any period presented, and accordingly, the ratio of earnings to combined fixed charges and preferred stock dividends is the same as the ratio of earnings to fixed charges.

American Water’s and AWCC’s ratios of earnings to fixed charges for each of the periods indicated are as follows:

SELLING SECURITY HOLDERS

We may register securities covered by this prospectus for re-offers and resales by any selling security holders who may be named in a prospectus supplement. Because American Water is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act, we may add secondary sales of securities by any selling

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security holders by filing a prospectus supplement with the SEC. We may register these securities to permit selling security holders to resell their securities when they deem appropriate. A selling security holder may resell all, a portion or none of their securities at any time and from time to time. We may register those securities for sale through an underwriter or other plan of distribution as set forth in a prospectus supplement. See “Plan of Distribution.”

Selling security holders may also sell, transfer or otherwise dispose of some or all of their securities in transactions exempt from the registration requirements of the Securities Act. We may pay all expenses incurred with respect to the registration of the securities owned by the selling security holders, other than underwriting fees, discounts or commissions, which will be borne by the selling security holders. A prospectus supplement will name the selling security holders and specify the amount of securities to be registered and sold and any other terms of the securities being sold by a selling security holder. The applicable prospectus supplement will also disclose whether any of the selling security holders has held any position or office with, has been employed by or otherwise has had a material relationship with us during the three years prior to the date of the applicable prospectus supplement.

DESCRIPTION OF CAPITAL STOCK

The following description of American Water’s common stock and preferred stock is not intended to be complete. For more information regarding the common stock and preferred stock that may be offered by this prospectus, please refer to American Water’s restated certificate of incorporation, which we refer to below as American Water’s “certificate of incorporation,” and American Water’s amended and restated bylaws, which we refer to below as American Water’s “bylaws.” The certificate of incorporation and bylaws are incorporated by reference as exhibits to the registration statement of which this prospectus is a part. The terms of these securities also may be affected by the General Corporation Law of the State of Delaware, which we refer to below as the DGCL.

General

American Water’s authorized capital stock consists of 500,000,000 shares of common stock, par value $0.01 per share, and 50,000,000 shares of preferred stock. As of April 26, 2018, there were 178,047,882 shares of common stock outstanding and no shares of preferred stock outstanding.

Common Stock

Voting Rights

Other than with respect to director elections, except as otherwise required by law, all matters to be voted on by American Water’s stockholders must be approved by a majority of the shares present in person or proxy at such meeting and entitled to vote on the subject matter. With respect to uncontested director elections, American Water’s bylaws require that in order to be elected, a director nominee must receive a majority of the votes cast (for this purpose, a majority of the votes cast means that the number of shares voted “for” a director nominee must exceed the number of votes cast “against” that nominee). For contested director elections where the number of nominees exceeds the number of directors to be elected, American Water’s bylaws require that the directors shall be elected by the vote of a plurality of the shares represented in person or by proxy at any such meeting and entitled to vote on the election of directors.

Dividends

Holders of common stock will share equally in any dividend declared by American Water’s board of directors, subject to the rights of the holders of any outstanding preferred stock.

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Liquidation Rights

In the event of any voluntary or involuntary liquidation, dissolution or winding up of American Water’s affairs, holders of American Water’s common stock would be entitled, after payment of the liquidation preference to all holders of any outstanding preferred stock, to share ratably in American Water’s assets that are legally available for distribution to stockholders after payment of liabilities. American Water must pay the applicable distribution to any holders of its preferred stock before it may pay distributions to the holders of its common stock.

Other Rights

American Water’s stockholders have no preemptive or other rights to subscribe for additional shares.

Preferred Stock

American Water’s board of directors may authorize the issuance of preferred stock from time to time in one or more series, without stockholder approval. Subject to the limits imposed by the DGCL, the board of directors is authorized to fix for any series of preferred stock the number of shares of such series and the voting powers (if any), designation, preferences and relative, participating, optional or other special rights, and qualifications, limitations or restrictions of such series. American Water’s board of directors is also authorized to increase or decrease the number of shares of any series, but not below the number of shares of that series then outstanding, without any further vote or action by American Water’s stockholders.

American Water’s board of directors may authorize the issuance of preferred stock with voting or conversion rights that affect adversely the voting power or other rights of American Water’s common stockholders. The issuance of preferred stock, while providing flexibility in connection with possible acquisitions and other corporate purposes, could have the effect of delaying, deferring or preventing a change in control, causing the market price of American Water’s common stock to decline, or impairing the voting and other rights of the holders of American Water’s common stock. Any restriction on the repurchase or redemption of shares of preferred stock while dividends on such shares are in arrears shall be set forth in the applicable prospectus supplement. You should read both this prospectus and the applicable prospectus supplement together with the additional information referred to below under “Where You Can Find More Information.”

For any series of preferred stock that American Water may issue, American Water’s board of directors will determine and the prospectus supplement relating to such series will describe:

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Certain Anti-Takeover Provisions of American Water’s Certificate of Incorporation and Bylaws, and the DGCL

The following provisions of American Water’s certificate of incorporation and bylaws could deter, delay or prevent a third party from acquiring American Water, even if doing so would benefit American Water’s stockholders.

Undesignated Preferred Stock

The ability to authorize undesignated preferred stock makes it possible for American Water’s board of directors to authorize the issuance of preferred stock with super voting, special approval, dividend or other rights or preferences on a discriminatory basis that could impede the success of any attempt to acquire American Water. These and other provisions may have the effect of deferring, delaying or discouraging hostile takeovers, or changes in control or management of American Water.

Requirements for Advance Notification of Stockholder Meetings, Nominations and Proposals

American Water’s bylaws provide that special meetings of stockholders may be called only upon the request of the majority of American Water’s board of directors, upon request of the Chairman of American Water’s board of directors, or by American Water’s Secretary upon request of stockholders holding at least 15% of American Water’s outstanding common stock. American Water’s bylaws prohibit the conduct of any business at a special meeting other than as specified in the notice for such meeting.

American Water’s bylaws establish advance notice procedures with respect to stockholder proposals for annual meetings and the nomination of candidates for election as directors, other than nominations made by or at the direction of American Water’s board of directors or a committee of the board of directors. A stockholder who wishes to bring a matter before a meeting must comply with American Water’s advance notice requirements and provide us with certain information. Additionally, vacancies and newly created directorships may be filled only by a vote of a majority of the directors then in office, even though less than a quorum, or by stockholders. These provisions may defer, delay or discourage a potential acquiror from conducting a solicitation of proxies to elect the acquiror’s own slate of directors or otherwise attempting to obtain control of American Water.

Stockholder Action by Written Consent

As permitted by Section 228 of the DGCL, American Water’s certificate of incorporation states that any action required or permitted to be taken by American Water’s stockholders must be effected at a duly called annual or special meeting of American Water’s stockholders and may not be effected by consent in writing by such stockholders.

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Acquisitions of Control of a Regulated Public Utility

A significant number of our regulated subsidiaries are subject to economic regulation by state public utility commissions. Some of these states have enacted laws that require regulatory approval for the acquisition of “control” of any regulated utility. In those states, obtaining “control” of the parent or any other company that controls a regulated utility also requires prior regulatory approval. The threshold for a change in control is a fact-specific inquiry that varies by state. For example, in some states, a presumption of control will arise when an acquiring party acquires more than 9.9% of the voting securities of the regulated utility or the controlling entity. In addition to ownership, other states may analyze the degree of influence or control an acquiror may exert over the company. Any person acquiring American Water’s common stock in an offering or in any other purchase of American Water’s common stock in an amount sufficient to trigger a change in control under state law would need to obtain the prior approval of the applicable state public utility commission.

Certain Other Provisions of American Water’s Certificate of Incorporation and Bylaws and Delaware Law

Board of Directors

American Water’s certificate of incorporation provides that the number of directors is fixed in the manner provided in American Water’s bylaws. American Water’s bylaws provide that the number of directors will be fixed from time to time by American Water’s board.

Business Combinations under Delaware Law

American Water is subject to Section 203 of the DGCL, which prohibits a publicly held Delaware corporation from engaging in a “business combination” with an “interested stockholder” for a period of three years after the time the stockholder became an interested stockholder, subject to certain exceptions, including if, prior to such time, the board of directors approved the business combination or the transaction which resulted in the stockholder becoming an interested stockholder. “Business combinations” include mergers, asset sales and other transactions resulting in a financial benefit to the “interested stockholder.” Subject to various exceptions, an “interested stockholder” is a person who, together with his or her affiliates and associates, owns, or within the prior three years did own, 15% or more of the corporation’s outstanding voting stock. These restrictions generally prohibit or delay the accomplishment of mergers or other takeover or change-in-control attempts that are not approved by a company’s board of directors.

Limitations of Liability and Indemnification of Officers and Directors

The DGCL authorizes corporations to limit or eliminate the personal liability of directors to corporations and their stockholders for monetary damages for breaches of directors’ fiduciary duties. American Water’s certificate of incorporation includes a provision that eliminates the personal liability of directors for monetary damages for actions taken as a director to the fullest extent authorized by the DGCL. The DGCL does not permit exculpation for liability:

American Water’s certificate of incorporation and bylaws provide that it will indemnify its directors and officers to the fullest extent permitted by law. American Water’s bylaws also expressly authorize American Water to carry directors’ and officers’ insurance providing indemnification for American Water’s directors, officers and certain employees and agents for some liabilities.

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The limitation of liability and indemnification provisions in American Water’s certificate of incorporation and bylaws may discourage stockholders from bringing a lawsuit against directors for breach of their fiduciary duty. These provisions may also have the effect of reducing the likelihood of derivative litigation against directors and officers, even though such an action, if successful, might otherwise benefit American Water and its stockholders. In addition, your investment may be adversely affected to the extent American Water pays the costs of settlement and damage awards against directors and officers in accordance with these indemnification provisions.

Transfer Agent and Registrar

American Stock Transfer & Trust Company, LLC serves as the registrar and transfer agent for American Water’s common stock.

New York Stock Exchange Symbol

American Water’s common stock is listed on the New York Stock Exchange under the trading symbol “AWK.”

DESCRIPTION OF AWCC DEBT SECURITIES AND AMERICAN WATER SUPPORT AGREEMENT

The following description of the terms of the debt securities sets forth certain general terms and provisions of the debt securities to which any prospectus supplement may relate. The particular terms of the debt securities offered by any prospectus supplement and the extent, if any, to which these general provisions may apply to those debt securities, will be described in the prospectus supplement relating to those debt securities. Accordingly, for a description of the terms of a particular issue of debt securities, reference must be made to both the prospectus supplement relating thereto and to the following description.

AWCC may issue debt securities from time to time in one or more series. The debt securities will be general obligations of AWCC. Any debt securities issued by AWCC will have the benefit of a support agreement from American Water. In the event that any series of debt securities will be subordinated to other indebtedness that AWCC has outstanding or may incur, the terms of the subordination will be set forth in the prospectus supplement relating to the subordinated debt securities. We expect that each series of debt securities will be issued under an indenture dated as of December 4, 2009, between AWCC and Wells Fargo Bank, National Association, as trustee, as the same may be amended or supplemented from time to time. The indenture and the form of supplemental indenture or other instrument establishing the debt securities of a particular series are filed as exhibits to, or will be subsequently incorporated by reference into, the registration statement of which this prospectus is a part. There is no requirement under the indenture that our future issuances of debt securities be issued exclusively under the indenture, and we will be free to employ other indentures or documentation, containing provisions different from those included in the indenture or applicable to one or more issuances of debt securities debt securities in connection with future issuances of other debt securities.

The following discussion of certain provisions of the indenture is a summary only and should not be considered a complete description of the terms and provisions of the indenture. Accordingly, the following discussion is qualified in its entirety by reference to the provisions of the indenture, including the definition of certain terms used below.

General

The debt securities represent direct, unsecured, general obligations of AWCC and:

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The aggregate principal amount of debt securities that AWCC may authenticate and deliver is unlimited. The debt securities may be issued in one or more series as we may authorize from time to time. You should refer to the applicable prospectus supplement for the following terms of the debt securities of the series with respect to which that prospectus supplement is being delivered:

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All debt securities of one series need not be issued at the same time, and a series may be re-opened for issuances of additional debt securities of such series. This means that AWCC may from time to time, without notice to, or the consent of any existing holders of the previously-issued debt securities of a particular series, create and issue additional debt securities of such series. Such additional debt securities will have the same terms as the previously-issued debt securities of such series in all respects except for the issue date, public offering

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price and, if applicable, the initial interest payment date. The additional debt securities will be consolidated and form a single series with the previously-issued debt securities of such series.

Support Agreement

AWCC’s indebtedness (including debt securities) has the benefit of the support agreement. The support agreement, which, under the circumstances described below, is the functional equivalent of a guarantee, provides, among other things, that:

No amendment to the support agreement that adversely affects the rights of any lender (including any holder of debt securities) and no termination of the support agreement will be effective until such time as all indebtedness of AWCC shall have been irrevocably paid in full and all commitments for indebtedness have been terminated, unless the lenders ( including holders of debt securities or the trustee acting on behalf of debt security holders) holding all of the aggregate principal amount of debt outstanding and (to the extent not outstanding) committed to consent in writing thereto. Notwithstanding the foregoing sentence, any amendment to the support agreement for the purposes of (i) increasing the minimum net worth as provided in the support agreement, (ii) establishing or increasing a minimum interest coverage ratio, (iii) establishing or reducing a maximum amount of debt leverage, (iv) increasing the aggregate principal amount of debt outstanding whose holders are required to consent to the termination or amendment of the support agreement, or (v) any combination of clauses (i), (ii), (iii) and (iv) of this sentence, shall be effective without the consent of any lender (including any holder of debt securities or trustee acting on behalf of such holder). In addition, nothing in the prior two sentences shall derogate from, or override, any provision in an instrument, indenture, agreement or other document pursuant to which indebtedness is or will be issued that requires the written consent of the holders of a specified amount or percentage of that indebtedness to consent to an amendment or termination of the support agreement.

Certain Covenants

If debt securities are issued, the indenture, as supplemented for a particular series of debt securities, may contain, among others, the following covenants for the benefit of the holders of such series of debt securities, which will be applicable (unless waived or amended) so long as any of the debt securities of such series are outstanding, unless stated otherwise in the prospectus supplement:

Restrictions on Liens

AWCC will not, and will not allow American Water, as the support provider, or any of its subsidiaries to, create, incur, issue or assume any liens on our or its respective property to secure debt where the debt secured by

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those liens would exceed an amount equal to 15% of our consolidated tangible total assets, as defined below (calculated to exclude debt secured by permitted liens). This restriction does not apply to the following permitted liens:

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“Debt” means, for any person (without duplication), all (i) indebtedness for borrowed money, (ii) obligations evidenced by bonds, debentures, debt securities or other similar instruments, (iii) obligations to pay the deferred purchase price of property or service (other than trade payables not overdue by more than 90 days incurred in the ordinary course of business and long term water purchase contracts), (iv) obligations

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under capital leases, (v) indebtedness of the type referred to in clauses (i) through (iv) above secured by (or for which the holder of such indebtedness has an existing right, contingent or otherwise, to be secured by), any lien or encumbrance on, or security interest in, property (including, without limitation, accounts and contract rights) owned by such person, even though such person has not assumed or become liable for payment of such indebtedness, and (vi) all obligations of such person for indebtedness or obligations of others of the kinds referred to in clauses (i) through (iv) above under direct or indirect guarantees, excluding, in all cases, (i) advances for construction and contributions in aid of construction as set forth on the consolidated balance sheet of American Water and its subsidiaries, (ii) reimbursement obligations (contingent or otherwise) in respect of outstanding letters of credit and (iii) attributable debt in respect of sale and leaseback transactions.

“Subsidiary” means a corporation more than 50% of the outstanding voting stock of which is owned, directly or indirectly, by American Water or by one or more other subsidiaries, or by American Water and one or more other subsidiaries.

Restrictions on Sales and Leasebacks

AWCC will not, and will not allow American Water or any of its subsidiaries to, enter into any sale and leaseback transaction without effectively providing that the debt securities will be secured equally and ratably with or prior to the sale and leaseback transaction, unless:

A “sale and leaseback transaction” for purposes of this subsection is an arrangement between AWCC, American Water or any of its subsidiaries and a bank, insurance company or other lender or investor where AWCC, American Water or any of its subsidiaries leases property for an initial term of three years or more that was or will be sold by AWCC, American Water, or such subsidiary to that lender or investor for a sale price of U.S. $1,000,000 or its equivalent or more.

“Attributable debt” means the lesser of (1) the fair market value of the asset subject to the sale and leaseback transaction and (2) the present value, determined in accordance with GAAP (discounted at a rate equal to the rate of interest implicit in such transaction), of the obligations of the lessee for the net rental payments (excluding amounts on account of maintenance and repairs, insurance, taxes, assessments and similar charges and contingent rents) during the term of the lease.

“Consolidated tangible total assets” means, as at any applicable time of determination, consolidated total assets less, without duplication, all intangible assets such as goodwill, trademarks, trade names, patents and unamortized debt discount and expense carried as an asset, in each case as set forth in our most recent consolidated balance sheet.

“Consolidated total assets” means, as at any applicable time of determination, our consolidated total assets as set forth in our most recent consolidated financial statements.

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Merger, Consolidation or Sale of Assets

Neither AWCC nor American Water will consolidate with or merge into any other person or convey, transfer or lease its properties and assets substantially as an entirety to any person, unless:

(i) the successor formed by a consolidation or the survivor of a merger or the person that acquires by conveyance, transfer or lease all or substantially all of the assets of AWCC or American Water as an entirety, as the case may be, is a person organized and existing under the laws of the United States or any State thereof (including the District of Columbia), and expressly assumes, in the case of American Water, the due and punctual payment of the principal of and any premium and interest on all the debt securities and the performance or observance of every covenant of the indenture on the part of AWCC to be performed or observed, and, in the case of American Water, all the obligations under the support agreement to be performed or observed, and such person shall have caused to be delivered to the trustee an officer’s certificate and an opinion of counsel to the effect that such consolidation, merger, conveyance, transfer or lease complies in all material respects with this covenant; and

(ii) immediately before and immediately after giving effect to such transaction, no event of default, and no event which, after notice or lapse of time or both, would become an event of default, has occurred and is continuing.

Upon any consolidation by AWCC or American Water with or merger by AWCC or American Water into any other person or any conveyance, transfer or lease of either AWCC’s or American Water’s properties and assets substantially as an entirety in accordance with this covenant, the successor person formed by such consolidation or into which it is merged or to which such conveyance, transfer or lease is made will succeed to, and be substituted for, and may exercise every right and power of, AWCC or American Water, as applicable, under the indenture and the support agreement with the same effect as if such successor person had been named as AWCC or American Water, as applicable, therein, and thereafter, except in the case of a lease, the predecessor person will be relieved of all obligations and covenants, in the case of AWCC under the indenture, the debt securities and, in the case of American Water, under the support agreement.

Support Agreement

American Water may not (a) cancel or terminate the support agreement or (b) amend or otherwise modify the terms of the support agreement, except in accordance with the support agreement. See “Support Agreement.”

Subordination

Debt securities of a series may be subordinated, which we refer to as subordinated debt securities, to senior indebtedness (as will be defined in the applicable prospectus supplement) to the extent set forth in the prospectus supplement relating thereto. To the extent we conduct operations through subsidiaries, the holders of debt securities (whether or not subordinated debt securities) will be structurally subordinated to the creditors of our subsidiaries, except to the extent such subsidiary is a guarantor of such series of debt.

Events of Default

Each of the following constitutes an event of default under the form of indenture with respect to any series of debt securities:

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A prospectus supplement may omit, modify or add to the foregoing events of default.

In the case of an event of default arising from certain events of bankruptcy or insolvency, with respect to AWCC or American Water, all outstanding debt securities in such series will become due and payable immediately without further action or notice. If any other event of default occurs and is continuing, the trustee or the holders of at least 25% in aggregate principal amount of the then outstanding debt securities in such series may declare all the securities to be due and payable immediately. Unless as otherwise provided herein, after any such acceleration, but before a judgment or decree based on acceleration is obtained by the trustee, the registered holders of a majority in aggregate principal amount of the outstanding debt securities in a series may, under certain circumstances, rescind and annul such acceleration and waive such event of default if all events of default, other than the nonpayment of accelerated principal, premium or interest have been cured or waived as provided in the indenture or a supplemental indenture.

Holders of a series of debt securities may not enforce the indenture, supplemental indenture or such debt securities except as provided in the indenture or supplemental indenture. Subject to certain limitations holders of a majority in principal amount of the then outstanding debt in a series may direct the trustee in its exercise of any trust or power. The trustee may withhold from holders of a series of debt securities notice of any continuing default if it determines that withholding notice is in their interest, except a default relating to the payment of principal or interest.

Subject to the provisions of the indenture relating to the duties of the trustee, in case an event of default shall occur and be continuing, the trustee will be under no obligation to exercise any of its rights or powers under

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the indenture at the request or direction of any of the holders of a series of debt securities, unless such holders shall have offered to the trustee reasonable indemnity or security against any loss, liability or expense. Subject to such provisions for indemnification of the trustee, the holders of a majority in aggregate principal amount of a series of debt securities then outstanding will have the right to direct the time, method and place of conducting any proceeding for any remedy available to the trustee or exercising any trust or power conferred on the trustee with respect to such series of outstanding debt securities.

The holders of a majority in aggregate principal amount of a series of debt securities then outstanding, by notice to the trustee, may, on behalf of the holders of all of such series of debt securities, waive any existing default and its consequences under the indenture except a continuing default in the payment of interest on, or the principal of, such series of debt securities (other than the non-payment of principal of or interest on such series of debt securities that became due solely because of the acceleration of such series of debt securities).

AWCC is required to deliver to the trustee within 90 days after the end of each fiscal year a statement regarding compliance with the indenture during that fiscal year. Promptly (and in any event within 5 business days) upon a responsible officer of AWCC becoming aware of any default or event of default, AWCC is required to deliver to the trustee a statement specifying that default.

“Responsible officer” means the chief executive officer, chief operating officer, general counsel, any senior financial officer and any other officer of AWCC with responsibility for the administration of the indenture.

“Senior financial officer” means the chief financial officer, principal accounting officer, treasurer or controller of AWCC.

Modification or Waiver

Except as provided below, AWCC and the trustee may supplement and amend the form of indenture or the debt securities with the consent of the holders of not less than a majority in principal amount of the outstanding debt securities. The consent of the holder of each outstanding debt security affected is required to:

AWCC and the trustee may supplement and amend the indenture or the debt securities without the consent of any holder for the following purposes:

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The consent of the holders of the debt securities is not necessary under the indenture to approve the particular form of any proposed amendment or supplemental indenture. It is sufficient if such consent approves the substance of the proposed amendment or supplemental indenture.

Prescription Period

Any money that AWCC deposits with the trustee or any paying agent for the payment of principal or interest on any global security that remains unclaimed for two years after the date upon which the principal and interest are due and payable will be repaid to AWCC upon AWCC’s request unless otherwise required by mandatory provisions of any applicable unclaimed property law. After that time, unless otherwise required by mandatory provisions of any unclaimed property law, the holder of any debt security will be able to seek any payment to which that holder may be entitled to collect only from AWCC.

No Personal Liability of Directors, Officers, Employees and Stockholders

No director, officer, employee, incorporator or stockholder of AWCC or us, will have any liability for any obligations of AWCC or American Water under the debt securities, the indenture, the support agreement, or for any claim based on, in respect of, or by reason of, such obligations or their creation. Each holder of debt securities by accepting a debt security waives and releases all such liability. The waiver and release are part of the consideration for issuance of the debt securities. The waiver may not be effective to waive liabilities under the federal securities law and it is the view of the SEC that such waiver is against public policy.

Defeasance

At any time, AWCC may terminate all its obligations under debt securities of a series and the indenture, which we refer to as legal defeasance, except for certain obligations, including those respecting the defeasance trust and obligations to register the transfer or exchange of debt securities of such series, to replace mutilated, destroyed, lost or stolen debt securities of such series and to maintain a registrar and paying agent in respect of the debt securities of such series.

In addition, at any time AWCC may terminate its obligations under certain specified covenants with respect to a series of debt securities.

AWCC may exercise its legal defeasance option with respect to a series of debt securities notwithstanding its prior exercise of its covenant defeasance option with respect to such series of debt securities. If AWCC exercises its legal defeasance option with respect to a series of debt securities, payment of the debt securities of

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such series may not be accelerated because of an event of default with respect thereto. If AWCC exercises its covenant defeasance option with respect to a series of debt securities, payment of the debt securities of such series may not be accelerated because of a default related to the specified covenants.

In order to exercise either of its defeasance options, AWCC must irrevocably deposit in trust, which we refer to as the defeasance trust, with the trustee money or U.S. Government obligations, or both, in an amount deemed sufficient in the opinion of a nationally recognized firm of public accountants for the payment of principal and interest on the applicable series of debt securities to redemption or maturity, as the case may be, and must comply with certain other conditions, including delivery to the trustee of an opinion of counsel to the effect that holders of the debt securities of such series will not recognize income, gain or loss for U.S. federal income tax purposes as a result of such deposit and defeasance and will be subject to U.S. Federal income tax on the same amounts and in the same manner and at the same times as would have been the case if such deposit and defeasance had not occurred (and, in the case of legal defeasance only, such opinion of counsel must be based on a ruling of the Internal Revenue Service or other change in applicable U.S. federal income tax law).

Discharge

When (i) AWCC delivers to the trustee all outstanding debt securities of a series (other than any debt securities replaced because of mutilation, loss, destruction or wrongful taking) for cancellation or (ii) all outstanding debt securities of such series have become due and payable, or are by their terms due and payable within one year whether at maturity or are to be called for redemption within one year under arrangements reasonably satisfactory to the trustee, and in the case of clause (ii) AWCC irrevocably deposits with the trustee funds sufficient to pay at maturity or upon redemption all outstanding debt securities of such series, including interest thereon, and if in either case AWCC pays all other sums related to the applicable series of debt securities payable under the indenture by AWCC, then the indenture shall, subject to certain surviving provisions cease to be of further effect with respect to such series. The trustee shall acknowledge satisfaction and discharge of the indenture with respect to the applicable series of debt securities on demand of AWCC accompanied by an officers’ certificate and an opinion of counsel of AWCC.

Governing Law

The indenture and the debt securities will be governed by, and construed in accordance with, the laws of the State of New York, without regard to conflicts of laws principles thereof.

Book-Entry, Delivery and Form

Except as set forth below or in the applicable prospectus supplement, each series of debt securities will be issued in registered, global form in minimum denominations of $1,000 and integral multiples of $1,000 in excess thereof. The debt securities will be issued at the closing of any offering only against payment in immediately available funds.

The debt securities initially will be represented by one or more global securities. Upon issuance, each of the global securities will be deposited with the trustee as custodian for The Depository Trust Company, which we refer to as “DTC”, in New York, New York, and registered in the name of DTC or its nominee, in each case for credit to an account of a direct or indirect participant in DTC as described below.

Except as set forth below, the global securities may be transferred, in whole and not in part, only to another nominee of DTC or to a successor of DTC or its nominee. Beneficial interests in the global securities may not be exchanged for definitive debt securities in registered certificated form, which we refer to as certificated debt securities, except in the limited circumstances described below. See “Exchange of Global Securities for Certificated Debt Securities.” Except in the limited circumstances described below, owners of beneficial interests in the global securities will not be entitled to receive physical delivery of the debt securities in certificated form.

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Transfers of beneficial interests in the global securities will be subject to the applicable rules and procedures of DTC and its direct or indirect participants, which may change from time to time.

Exchanges of Global Securities for Certificated Debt Securities

A beneficial interest in a global security may not be exchanged for a debt security in certificated form unless (i) DTC (x) notifies AWCC that it is unwilling or unable to continue as depository for such global security or (y) has ceased to be a clearing agency registered under the Exchange Act, or (ii) there shall have occurred and be continuing an event of default with respect to the debt securities. In all cases, certificated debt securities delivered in exchange for any global security or beneficial interests therein will be registered in the names, and issued in approved denominations, requested by or on behalf of DTC (in accordance with its customary procedures). Any certificated debt securities issued in exchange for an interest in a global security will bear the legend restricting transfers that is borne by such global security. Any such exchange will be effected only through the DWAC system and an appropriate adjustment will be made in the records of the security register to reflect a decrease in the principal amount of the relevant global security.

Depository Procedures

The following description of the operations and procedures of DTC is provided solely as a matter of convenience. These operations and procedures are solely within the control of the respective settlement systems and are subject to changes by them from time to time. American Water and AWCC take no responsibility for these operations and procedures and urge investors to contact the system or their participants directly to discuss these matters.

Upon the issuance of the global securities, DTC will credit, on its internal system, the respective principal amount of the individual beneficial interests represented by such global securities to the accounts with DTC, which we refer to as participants, or persons who hold interests through participants. Ownership or beneficial interests in the global securities will be shown on, and the transfer of that ownership will be effected only through, records maintained by DTC or its nominee (with respect to interests of participants) and the records of participants (with respect to interest of persons other than participants).

As long as DTC, or its nominee, is the registered holder of a global security, DTC or such nominee, as the case may be, will be considered the sole owner and holder of the debt securities represented by such global security for all purposes under the indenture and the debt securities. Except in the limited circumstances described above under “—Exchanges of Global Securities for Certificated Debt Securities,” owners of beneficial interests in a global security will not be entitled to have portions of such global security registered in their names, will not receive or be entitled to receive physical delivery of debt securities in definitive form and will not be considered the owners or holders of the global security (or any debt securities presented thereby) under the indenture or the debt securities. In addition, no beneficial owner of an interest in a global security will be able to transfer that interest except in accordance with DTC’s applicable procedures (in addition to those under the indenture referred to herein). In the event that owners of beneficial interests in a global security become entitled to receive debt securities in definitive form, such debt securities will be issued only in registered form in denominations of U.S. $1,000 and integral multiples of $1,000 in excess thereof.

Investors may hold their interests in the global securities directly through DTC, if they are participants in such system, or indirectly through organizations which are participants in such system. All interests in a global security may be subject to the procedures and requirements of DTC.

The laws of some states require that certain persons take physical delivery in definitive form of securities that they own. Consequently, the ability to transfer beneficial interests in a global security to such persons may be limited to that extent. Because DTC can act only on behalf of participants, which in turn act on behalf of indirect participants and certain banks, the ability of a person having beneficial interests in a global security to

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pledge such interests to persons or entities that do not participate in the DTC system, or otherwise take action in respect of such interests, may be affected by the lack of a physical certificate evidencing such interests.

Payments of the principal of and interest on global securities will be made to DTC or its nominee as the registered owner thereof. Neither AWCC, the trustee nor any of their respective agents will have any responsibility or liability for any aspect of the records relating to or payments made on account of beneficial ownership interests in the global securities or for maintaining, supervising or reviewing any records relating to such beneficial ownership interests.

Beneficial interests in the global securities will trade in DTC’s Same-Day Funds Settlement System, and secondary market trading activity in such interests will therefore settle in immediately available funds. AWCC expects that DTC or its nominee, upon receipt of any payment of principal or interest in respect of a global security representing any debt securities held by it or its nominee, will immediately credit participants’ accounts with payment in amounts proportionate to their respective beneficial interests in the principal amount of such debt securities as shown on the records of DTC or its nominee. AWCC also expects that payments by participants to owners of beneficial interests in such global securities held through such participants will be governed by standing instructions and customary practices, as is the case with securities held for the accounts of customers registered in “street name.” Such payments will be the responsibility of such participants.

Transfers between participants in DTC will be effected in accordance with DTC’s procedures, and will be settled in same-day funds.

DTC has advised AWCC that it will take any action permitted to be taken by a holder of debt securities (including the presentation of debt securities for exchange as described below) only at the direction of one or more participants to whose account with DTC interests in the global securities are credited and only in respect of such portion of the aggregate principal amount of the debt securities as to which such participant or participants has or have given such direction. However, if there is an event of default under the debt securities, DTC reserves the right to exchange the global securities for legended debt securities in certificated form, and to distribute such debt securities to its participants.

DTC has advised AWCC that DTC is:

DTC was created to hold securities for its participants and facilitate the clearance and settlement of securities transactions between participants through electronic book-entry changes in accounts of its participants, thereby eliminating the need for physical transfer and delivery of certificates. Participants include securities brokers and dealers, banks, trust companies and clearing corporations and may include certain other organizations. DTC is partially owned by some of these participants or their representatives. Indirect access to the DTC system is available to other entities such as banks, brokers, dealers and trust companies that clear through or maintain a custodial relationship with a participant, either directly or indirectly, which we refer to as indirect participants.

Although DTC has agreed to the foregoing procedures in order to facilitate transfers of beneficial ownership interests in the global securities among participants of DTC, it is under no obligation to perform or continue to

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perform such procedures, and such procedures may be discontinued at any time. None of AWCC, the trustee nor any of their respective agents will have any responsibility for the performance by DTC or its participants or indirect participants of its respective obligations under the rules and procedures governing its operations, including maintaining, supervising or reviewing the records relating to, or payments made on account of, beneficial ownership interests in global securities.

Same Day Settlement and Payment

AWCC will make payments in respect of the debt securities represented by the global securities (including principal, premium, if any, interest and special interest, if any) by wire transfer of immediately available funds to the accounts specified by the global security holder. AWCC will make all payments of principal, interest and premium and special interest, if any, with respect to certificated debt securities by wire transfer of immediately available funds to the accounts specified by the holders of the certificated debt securities or, if no such account is specified, by mailing a check to each such holder’s registered address. The debt securities represented by the global securities are expected to be eligible to trade in DTC’s Same-Day Funds Settlement System, and any permitted secondary market trading activity in such debt securities will, therefore, be required by DTC to be settled in immediately available funds. AWCC expects that secondary trading in any certificated debt securities will also be settled in immediately available funds.

DESCRIPTION OF DEPOSITARY SHARES

The following summary of certain provisions of the depositary shares does not purport to be complete and is subject to, and qualified in its entirety by reference to, the provisions of the depositary agreement that will be filed with the SEC in connection with the offering of such depositary shares.

American Water may offer fractional shares of preferred stock, rather than full shares of preferred stock. If American Water decides to offer fractional shares of preferred stock, American Water will issue receipts for depositary shares. Each depositary share will represent a fraction of a share of a particular series of preferred stock, and the prospectus supplement will indicate that fraction. The shares of preferred stock represented by depositary shares will be deposited under a depositary agreement between American Water and a depositary that is a bank or trust company that meets certain requirements and is selected by us. The depositary will be specified in the applicable prospectus supplement. Each owner of a depositary share will be entitled to all of the rights and preferences of the preferred stock represented by the depositary share. The depositary shares will be evidenced by depositary receipts issued pursuant to the depositary agreement. Depositary receipts will be distributed to those persons purchasing the fractional shares of preferred stock in accordance with the terms of the offering.

We have summarized selected provisions of the depositary agreement and the depositary receipts, but the summary is qualified in its entirety by reference to the provisions of the depositary agreement and the depositary receipts. The particular terms of any series of depositary shares will be described in the applicable prospectus supplement. If so indicated in the prospectus supplement, the terms of any such series may differ from the terms set forth below.

Dividends and Other Distributions

The depositary will distribute all cash dividends or other cash distributions received by it in respect of the preferred stock to the record holders of depositary shares relating to such preferred shares in proportion to the numbers of depositary shares held on the relevant record date. The amount made available for distribution will be reduced by any amounts withheld by the depositary or American Water on account of taxes.

In the event of a distribution other than in cash, the depositary will distribute securities or property received by it to the record holders of depositary shares in proportion to the numbers of depositary shares held on the

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relevant record date, unless the depositary determines that it is not feasible to make such distribution. In that case, the depositary may make the distribution by such method as it deems equitable and practicable. One such possible method is for the depositary to sell the securities or property and then distribute the net proceeds from the sale as provided in the case of a cash distribution.

Withdrawal of Shares

Upon surrender of depositary receipts representing any number of whole shares at the depositary’s office, unless the related depositary shares previously have been called for redemption, the holder of the depositary shares evidenced by the depositary receipts will be entitled to delivery of the number of whole shares of the related series of preferred stock and all money and other property, if any, underlying such depositary shares. However, once such an exchange is made, the preferred stock cannot thereafter be redeposited in exchange for depositary shares. Holders of depositary shares will be entitled to receive whole shares of the related series of preferred stock on the basis set forth in the applicable prospectus supplement. If the depositary receipts delivered by the holder evidence a number of depositary shares representing more than the number of whole shares of preferred stock of the related series to be withdrawn, the depositary will deliver to the holder at the same time a new depositary receipt evidencing the excess number of depositary shares.

Redemption of Depositary Shares

Whenever American Water redeems the preferred stock, the depositary will redeem a number of depositary shares representing the same number of shares of preferred stock so redeemed. If fewer than all of the depositary shares are to be redeemed, the depositary shares to be redeemed will be selected by lot, pro-rata or by any other equitable method as the depositary may determine.

Voting of Underlying Shares

Upon receipt of notice of any meeting at which the holders of the preferred stock of any series are entitled to vote, the depositary will mail the information contained in the notice of the meeting to the record holders of the depositary shares relating to that series of preferred shares. Each record holder of the depositary shares on the record date will be entitled to instruct the depositary as to the exercise of the voting rights represented by the number of shares of preferred stock underlying the holder’s depositary shares. The depositary will endeavor, to the extent it is practical to do so, to vote the number of whole shares of preferred stock underlying such depositary shares in accordance with such instructions. American Water will agree to take all action that the depositary may deem reasonably necessary in order to enable the depositary to do so. To the extent the depositary does not receive specific instructions from the holders of depositary shares relating to such preferred shares, it will abstain from voting such shares of preferred stock.

Amendment and Termination of Depositary Agreement

The form of depositary receipt evidencing the depositary shares and any provision of the applicable depositary agreement may at any time be amended by agreement between American Water and the depositary. American Water may, with the consent of the depositary, amend the depositary agreement from time to time in any manner that American Water desires. However, if the amendment would materially and adversely alter the rights of the existing holders of depositary shares, the amendment would need to be approved by the holders of at least a majority of the depositary shares then outstanding.

The depositary agreement may be terminated by American Water or the depositary if:

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Resignation and Removal of Depositary

The depositary may resign at any time by delivering to us notice of its election to do so. We may remove a depositary at any time. Any resignation or removal will take effect upon the appointment of a successor depositary and its acceptance of appointment.

Charges of Depositary

We will pay all transfer and other taxes and governmental charges arising solely from the existence of any depositary arrangements. We will pay all charges of each depositary in connection with the initial deposit of the preferred shares of any series, the initial issuance of the depositary shares, any redemption of such preferred shares and any withdrawals of such preferred shares by holders of depositary shares. Holders of depositary shares will be required to pay any other transfer taxes.

Notices

Each depositary will forward to the holders of the applicable depositary shares all notices, reports and communications from us which are delivered to such depositary and which we are required to furnish to the holders of the preferred shares.

Limitation of Liability

The depositary agreement contains provisions that limit our liability and the liability of the depositary to the holders of depositary shares. Both the depositary and we are also entitled to an indemnity from the holders of the depositary shares prior to bringing, or defending against, any legal proceeding. We or any depositary may rely upon written advice of counsel or accountants, or information provided by persons presenting preferred shares for deposit, holders of depositary shares or other persons believed by us to be competent and on documents believed by us or them to be genuine.

DESCRIPTION OF STOCK PURCHASE CONTRACTS AND STOCK PURCHASE UNITS

The following summary of certain provisions of the stock purchase contracts and stock purchase units does not purport to be complete and is subject to, and qualified in its entirety by reference to, the provisions of the stock purchase contract or stock purchase unit, as applicable, that will be filed with the SEC in connection with the offering of such securities.

American Water may issue stock purchase contracts, including contracts obligating holders to purchase from us, and obligating American Water to sell to the holders, a specified number of shares of common stock or other securities at a future date or dates, which we refer to in this prospectus as “stock purchase contracts.” The price per share of the securities and the number of shares of the securities may be fixed at the time the stock purchase contracts are issued or may be determined by reference to a specific formula set forth in the stock purchase contracts. The stock purchase contracts may be issued separately or as part of units consisting of a stock purchase contract and debt securities, preferred securities, warrants or debt obligations of third parties, including U.S. treasury securities, securing the holders’ obligations to purchase the securities under the stock purchase contracts, which we refer to herein as “stock purchase units.” The stock purchase contracts may require holders to secure their obligations under the stock purchase contracts in a specified manner. The stock purchase contracts also may require American Water to make periodic payments to the holders of the stock purchase units or vice versa, and those payments may be unsecured or refunded on some basis.

The applicable prospectus supplement will describe the terms of the stock purchase contracts or stock purchase units. The description in the prospectus supplement will not necessarily be complete, and reference will

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be made to the stock purchase contracts, and, if applicable, collateral or depositary arrangements, relating to the stock purchase contracts or stock purchase units, which will be filed with the SEC each time American Water issues stock purchase contracts or stock purchase units. Material U.S. federal income tax considerations applicable to the stock purchase units and the stock purchase contracts will also be discussed in the applicable prospectus supplement.

DESCRIPTION OF SUBSCRIPTION RIGHTS

The following summary of certain provisions of the subscription rights does not purport to be complete and is subject to, and qualified in its entirety by reference to, the provisions of the certificate evidencing the subscription rights that will be filed with the SEC in connection with the offering of such subscription rights.

General

American Water may issue subscription rights to purchase common stock, preferred stock, depositary shares or warrants to purchase preferred stock, common stock or depositary shares. Subscription rights may be issued independently or together with any other offered security and may or may not be transferable by the person purchasing or receiving the subscription rights. In connection with any subscription rights offering to American Water’s stockholders, American Water may enter into a standby underwriting arrangement with one or more underwriters pursuant to which such underwriters will purchase any offered securities remaining unsubscribed for after such subscription rights offering. In connection with a subscription rights offering to American Water’s stockholders, American Water will distribute certificates evidencing the subscription rights and a prospectus supplement to American Water’s stockholders on or about the record date that American Water sets for receiving subscription rights in such subscription rights offering.

The applicable prospectus supplement will describe the following terms of subscription rights in respect of which this prospectus is being delivered:

Exercise of Subscription Rights

Each subscription right will entitle the holder of the subscription right to purchase for cash such amount of shares of preferred stock, depositary shares, common stock, warrants or any combination thereof, at such

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exercise price as shall in each case be set forth in, or be determinable as set forth in, the prospectus supplement relating to the subscription rights offered thereby. Subscription rights may be exercised at any time up to the close of business on the expiration date for such subscription rights set forth in the prospectus supplement. After the close of business on the expiration date, all unexercised subscription rights will become void.

Subscription rights may be exercised as set forth in the prospectus supplement relating to the subscription rights offered thereby. Upon receipt of payment and the subscription rights certificate properly completed and duly executed at the corporate trust office of the subscription rights agent or any other office indicated in the prospectus supplement, American Water will forward, as soon as practicable, the shares of preferred stock or common stock, depositary shares or warrants purchasable upon such exercise. American Water may determine to offer any unsubscribed offered securities directly to persons other than stockholders, to or through agents, underwriters or dealers or through a combination of such methods, including pursuant to standby underwriting arrangements, as set forth in the applicable prospectus supplement.

DESCRIPTION OF WARRANTS

The following summary of certain provisions of the warrants does not purport to be complete and is subject to, and qualified in its entirety by reference to, the provisions of the warrant agreement that will be filed with the SEC in connection with the offering of such warrants.

General

American Water may issue warrants for the purchase of debt securities, preferred stock or common stock. Warrants may be issued independently or together with debt securities, preferred stock or common stock offered by any prospectus supplement and may be attached to or separate from any such offered securities. Each series of warrants will be issued under a separate warrant agreement to be entered into between American Water and a bank or trust company, as warrant agent. The warrant agent will act solely as American Water’s agent in connection with the warrants and will not assume any obligation or relationship of agency or trust for or with any holders or beneficial owners of warrants.

Debt Warrants

The prospectus supplement relating to a particular issue of debt warrants will describe the terms of such debt warrants, including the following:

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Stock Warrants

The prospectus supplement relating to any particular issue of preferred stock warrants or common stock warrants will describe the terms of such warrants, including the following:

(m) any provisions for changes to or adjustments in the exercise price for the stock warrants; and

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PLAN OF DISTRIBUTION

We and any selling security holder may offer and sell the securities covered by this prospectus from time to time, in one or more transactions, at market prices prevailing at the time of sale, at prices related to market prices, at a fixed price or prices subject to change, at varying prices determined at the time of sale or at negotiated prices, by a variety of methods, including the following:

Registration of the securities covered by this prospectus does not mean that those securities necessarily will be offered or sold.

In effecting sales, brokers or dealers engaged by us may arrange for other brokers or dealers to participate. Broker-dealer transactions may include:

In addition, we and any selling security holder may sell any securities covered by this prospectus in private transactions or under Rule 144 of the Securities Act rather than pursuant to this prospectus.

In connection with the sale of securities covered by this prospectus, broker-dealers may receive commissions or other compensation from us in the form of commissions, discounts or concessions. Broker-dealers may also receive compensation from purchasers of the securities for whom they act as agents or to whom they sell as principals or both. Compensation as to a particular broker-dealer may be in excess of customary commissions or in amounts to be negotiated. In connection with any underwritten offering, underwriters may receive compensation in the form of discounts, concessions or commissions from us or from purchasers of the securities for whom they act as agents. Underwriters may sell the securities to or through dealers, and such dealers may receive compensation in the form of discounts, concessions or commissions from the underwriters and/or commissions from the purchasers for whom they may act as agents. Any underwriters, broker-dealers, agents or other persons acting on our behalf that participate in the distribution of the securities may be deemed to be “underwriters” within the meaning of the Securities Act, and any profit on the sale of the securities by them and any discounts, commissions or concessions received by any of those underwriters, broker-dealers, agents or other persons may be deemed to be underwriting discounts and commissions under the Securities Act.

In connection with the distribution of the securities covered by this prospectus or otherwise, we or any selling security holder may enter into hedging transactions with broker-dealers or other financial institutions. In connection with such transactions, broker-dealers or other financial institutions may engage in short sales of our securities in the course of hedging the positions they assume with us or any selling security holder. We or any selling security holder may also sell securities short and deliver the securities offered by this prospectus to close out our short positions. We or any selling security holder may also enter into option or other transactions with broker-dealers or other financial institutions, which require the delivery to such broker-dealer or other financial institution of securities offered by this prospectus, which securities such broker-dealer or other financial

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institution may resell pursuant to this prospectus, as supplemented or amended to reflect such transaction. We or any selling security holder may also from time to time pledge our securities pursuant to the margin provisions of our customer agreements with our brokers. Upon our default, the broker may offer and sell such pledged securities from time to time pursuant to this prospectus, as supplemented or amended to reflect such transaction.

At any time a particular offer of the securities covered by this prospectus is made, a prospectus supplement, or, if required, a revised prospectus, will be distributed which will set forth the aggregate amount of securities covered by this prospectus being offered and the terms of the offering, including the name or names of any underwriters, dealers, brokers or agents, any discounts, commissions, concessions and other items constituting compensation from us and any discounts, commissions or concessions allowed or reallowed or paid to dealers. Such prospectus supplement, and, if necessary, a post-effective amendment to the registration statement of which this prospectus is a part, will be filed with the SEC to reflect the disclosure of additional information with respect to the distribution of the securities covered by this prospectus. In order to comply with the securities laws of certain states, if applicable, the securities sold under this prospectus may only be sold through registered or licensed broker-dealers. In addition, in some states the securities may not be sold unless they have been registered or qualified for sale in the applicable state or an exemption from registration or qualification requirements is available and is complied with.

We may solicit offers to purchase directly. Offers to purchase securities also may be solicited by agents designated by us from time to time. Any such agent involved in the offer or sale of the securities in respect of which this prospectus is delivered will be named, and any commissions payable by us to such agent will be set forth, in the applicable prospectus supplement. Unless otherwise indicated in such prospectus supplement, any such agent will be acting on a reasonable best efforts basis for the period of its appointment. Any such agent may be deemed to be an underwriter, as that term is defined in the Securities Act, of the securities so offered and sold.

American Water may offer its equity securities into an existing trading market on the terms described in the applicable prospectus supplement. Underwriters, dealers and agents who may participate in any at-the-market offerings will be described in the prospectus supplement relating thereto.

Securities may also be offered and sold, if so indicated in the applicable prospectus supplement, in connection with a remarketing upon their purchase, in accordance with a redemption or repayment pursuant to their terms, or otherwise, by one or more firms acting as principals for their own accounts or as agents for us, which we refer to as remarketing firms. Any

remarketing firm will be identified and the terms of its agreement, if any, with us and its compensation will be described in the applicable prospectus supplement. Remarketing firms may be deemed to be underwriters, as that term is defined in the Securities Act, in connection with the securities remarketed thereby.

If so indicated in the applicable prospectus supplement, we may authorize agents, dealers or underwriters to solicit offers by certain institutions to purchase securities from us at the public offering price set forth in the applicable prospectus supplement pursuant to delayed delivery contracts providing for payment and delivery on the date or dates stated in the applicable prospectus supplement. Such delayed delivery contracts will be subject to only those conditions set forth in the applicable prospectus supplement. A commission indicated in the applicable prospectus supplement will be paid to underwriters and agents soliciting purchases of securities pursuant to delayed delivery contracts accepted by us.

In connection with an underwritten offering, we and any selling security holder would execute an underwriting agreement with an underwriter or underwriters. Unless otherwise indicated in the revised prospectus or applicable prospectus supplement, such underwriting agreement would provide that the obligations of the underwriter or underwriters are subject to certain conditions precedent, and that the underwriter or underwriters with respect to a sale of the covered securities will be obligated to purchase all of the covered securities, if any such securities are purchased. We or any selling security holder may grant to the underwriter or

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underwriters an option to purchase additional securities at the public offering price, less any underwriting discount, as may be set forth in the revised prospectus or applicable prospectus supplement. If we or any selling security holder grants any such option, the terms of that option will be set forth in the revised prospectus or applicable prospectus supplement.

Underwriters, agents, brokers or dealers may be entitled, pursuant to relevant agreements entered into with us, to indemnification by us or any selling security holder against certain civil liabilities, including liabilities under the Securities Act that may arise from any untrue statement or alleged untrue statement of a material fact, or any omission or alleged omission to state a material fact in this prospectus, any supplement or amendment hereto, or in the registration statement of which this prospectus forms a part, or to contribution with respect to payments which the underwriters, agents, brokers or dealers may be required to make.

LEGAL MATTERS

The validity of the securities offered in this prospectus and any related prospectus supplement and certain legal matters will be passed upon for us by Morgan, Lewis & Bockius LLP, New York, New York, and/or counsel named in the applicable prospectus supplement. If the securities are being distributed in an underwritten offering, certain legal matters will be passed upon for the underwriters by counsel identified in the related prospectus supplement.

EXPERTS

The consolidated financial statements and management’s assessment of the effectiveness of internal control over financial reporting (which is included in Management’s Report on Internal Control over Financial Reporting) incorporated in this prospectus by reference to the Annual Report on Form 10-K for the year ended December 31, 2017, have been so incorporated in reliance on the report of PricewaterhouseCoopers LLP, an independent registered public accounting firm, given on the authority of said firm as experts in auditing and accounting.

WHERE YOU CAN FIND MORE INFORMATION

We file annual, quarterly and current reports, proxy statements and other information with the SEC. These SEC filings are available to the public over the Internet at the SEC’s website at http://www.sec.gov and our website at https://amwater.com. You may also read and copy any document we file with the SEC at the SEC’s public reference room at 100 F Street, N.E., Washington, D.C. 20549. Please call the SEC at 1-800-SEC-0330 for further information on the public reference room. The information contained on or accessible from our website does not constitute a part of this prospectus and is not incorporated by reference herein.

We are “incorporating by reference” into this prospectus specific documents that we file with the SEC, which means that we can disclose important information to you by referring you to those documents that are considered part of this prospectus. Information that we file subsequently with the SEC will automatically update and supersede this information. We incorporate by reference the documents listed below, and any future documents that we file with the SEC under Section 13(a), 13(c), 14 or 15(d) of the Exchange Act, until the termination of the offerings of all of the securities covered by this prospectus. This prospectus is part of a registration statement filed with the SEC.

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We are “incorporating by reference” into this prospectus the following documents filed with the SEC (excluding any portions of such documents that have been “furnished” but not “filed” for purposes of the Exchange Act):

We will provide to each person, including any beneficial owner, to whom a prospectus is delivered, upon written or oral request and without charge, a copy of the documents referred to above that we have incorporated in this prospectus by reference. You can request copies of such documents if you write to us at the following address or call us at the following telephone number: American Water Works Company, Inc., 1025 Laurel Oak Road, Voorhees, New Jersey 08043, Attention: General Counsel, (856) 346-8200, or such other address and telephone number as may be provided in a prospectus supplement.

This prospectus, any accompanying prospectus supplement or information incorporated by reference herein or therein, contains summaries of certain agreements that we have filed as exhibits to various SEC filings, as well as certain agreements that we will enter into in connection with the offering of securities covered by any particular accompanying prospectus supplement. The descriptions of these agreements contained in this prospectus, any accompanying prospectus supplement or information incorporated by reference herein or therein do not purport to be complete and are subject to, and qualified in their entirety by reference to, the definitive agreements. Copies of the definitive agreements will be made available without charge to you by making a written or oral request to us.

You should rely only upon the information contained in this prospectus, any prospectus supplement or incorporated by reference into this prospectus or in any prospectus supplement. We have not authorized anyone to provide you with different information. You should not assume that the information in this prospectus is accurate as of any date other than that on the front cover of this prospectus.

Any statement contained herein or in a document incorporated or deemed to be incorporated by reference herein shall be deemed to be modified or superseded for purposes of this prospectus to the extent that a statement contained herein, in any other subsequently filed document which also is or is deemed to be incorporated by reference herein or in any accompanying prospectus supplement, modifies or supersedes such statement. Any such statement so modified or superseded shall not be deemed, except as so modified and superseded, to constitute a part of this prospectus.

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American Water Capital Corp.

$             % Senior Notes due 2028

$             % Senior Notes due 2048

Joint Book-Running Managers

Mizuho Securities

MUFG

RBC Capital Markets

TD Securities

BofA Merrill Lynch

PNC Capital Markets LLC

Co-Managers

J.P. Morgan

US Bancorp

Wells Fargo Securities

BB&T Capital Markets

Regions Securities LLC

Blaylock Van, LLC

C.L. King & Associates

Loop Capital Markets

MFR Securities, Inc.

Mischler Financial Group, Inc.

Multi-Bank Securities, Inc.

Ramirez & Co., Inc.

Siebert Cisneros Shank & Co., L.L.C.

Telsey Advisory Group

The Williams Capital Group, L.P.

Prospectus Supplement dated August     , 2018