美国水业美股招股说明书(2025-12-31版)

To the Shareholders of American Water Works Company, Inc. and Essential Utilities, Inc.: On behalf of the board of directors of American Water Works Company, Inc., which is referred to as American Water, and Essential Utilities, Inc., whichis referred to as Essential, we are pleased to enclose the accompanying joint proxy statement/prospectus relating to the proposed merger of AmericanWater and Essential. We are requesting that you take certain actions as a holder of American Water common stock or Essential common stock, as morefully described in the accompanying joint proxy statement/prospectus. Each of the boards of directors of American Water and Essential has authorized, adopted, and approved, and determined to be advisable, an Agreementand Plan of Merger, dated as of October26, 2025, which, as it may be amended from time to time, is referred to as the merger agreement, by and amongAmerican Water, Alpha Merger Sub, Inc., a direct, wholly owned subsidiary of American Water, which is referred to as Merger Sub, and Essential,pursuant to which the parties agreed to combine their respective companies in an all-stock merger transaction. Subject to the terms and conditions of themerger agreement, which are more fully described in the accompanying joint proxy statement/prospectus, Merger Sub will merge with and intoEssential, which transaction is referred to as the merger, with Essential surviving the merger as a wholly owned subsidiary of American Water. At the effective time of the merger, which is referred to as the effective time, each share of common stock, par value $0.50 per share, of Essential, whichis referred to as Essential common stock, issued and outstanding immediately prior to the effective time, other than any shares of Essential commonstock owned by American Water or Merger Sub or by Essential as treasury stock (in each case, other than Essential restricted shares), will be convertedinto the right to receive 0.305 shares, which is referred to as the exchange ratio, of validly issued, fully paid, and nonassessable common stock, par value$0.01 per share, of American Water, which is referred to as American Water common stock. The aggregate number of such shares of American Watercommon stock to be issued in the merger is collectively referred to as the merger consideration. The exchange ratio is fixed and will not be adjusted toreflect stock price changes of either American Water common stock or Essential common stock between the dates of the merger agreement and thecompletion of the merger. American Water shareholders will continue to own their existing shares of common stock of American Water after completionof the merger, the form of which will not be changed by the merger. Upon completion of the merger, former Essential shareholders will own approximately 31% of the then outstanding American Water common stock andAmerican Water shareholders will own the remaining approximately 69%, based on the number of shares of common stock and stock-based awards ofAmerican Water and Essential outstanding as of December29, 2025, the last practicable trading day before the date of the accompanying joint proxystatement/prospectus. American Water will issue a fixed number of shares of American Water common stock in exchange for each share of Essential common stock. As aresult, the implied value of the merger consideration to be received by Essential shareholders will fluctuate based on any changes in the market price ofAmerican Water common stock prior to the completion of the merger. Accordingly, such implied value of the per share merger consideration to bereceived by Essential shareholders upon completion of the merger could be greater than, less than, or the same as the implied value of the mergerconsideration on the date of the accompanying joint proxy statement/prospectus. We urge you to obtain current market quotations for the shares ofAmerican Water common stock and Essential common stock. American Water common stock is listed on the New York Stock Exchange, which isreferred to as the NYSE, under the symbol “AWK,” and Essential common stock is listed on the NYSE under the symbol “WTRG.” Table of Contents The merger is intended to qualify as a “reorganization” within the meaning of Section368(a) of the U.S. Internal Revenue Code of 1986, as amended.The obligation of the parties to consummate the merger is not conditioned upon the receipt of an opinion from counsel, nor have the parties applied for aruling from the U.S. Internal Revenue Service, that the merger would so qualify. Each of American Water and Essential will hold a special meeting of its shareholders in connection with the transactions contemplated by the merger American Water’s special meeting of shareholders will be held virtually (and not at a physical location) on February10, 2026 at10:00 a.m., Eastern time(unless it is adjourned or postponed to a later date) via remote communication atwww.virtualshareholdermeeting.com/AWK2026SM.