On behalf of the boards of directors of Xylem Inc. (“Xylem”) and Evoqua Water Technologies Corp. (“Evoqua”), we are pleased to enclose the accompanying joint proxy statement/prospectus relating to the merger of Xylem and Evoqua. We are requesting that you take certain actions as a Xylem shareholder or an Evoqua stockholder.

On January 22, 2023, Xylem, Fore Merger Sub, Inc., a Delaware corporation and a direct, wholly-owned subsidiary of Xylem (“Merger Sub”), and Evoqua entered into an Agreement and Plan of Merger (as amended from time to time, the “Merger Agreement”), providing for the merger of Merger Sub with and into Evoqua, with Evoqua surviving the merger as a direct, wholly-owned subsidiary of Xylem (the “Merger”). In the Merger, Evoqua stockholders will be entitled to receive, in exchange for each share of Evoqua common stock, par value $0.01 per share (“Evoqua Common Stock”), owned by them immediately prior to the Merger, 0.48 shares of Xylem common stock, par value $0.01 per share (“Xylem Common Stock”), with cash paid in lieu of the issuance of any fractional shares, which we refer to collectively as the “Merger Consideration.”

Xylem and Evoqua will each hold special meetings of their shareholders and stockholders, respectively, in connection with the proposed Merger (respectively, the “Xylem Special Meeting” and the “Evoqua Special Meeting”).

At the Xylem Special Meeting, holders of Xylem Common Stock (the “Xylem shareholders”) will be asked to vote on proposals to (i) approve the issuance of shares of Xylem Common Stock to the holders of Evoqua Common Stock (the “Evoqua stockholders”) in connection with the Merger pursuant to the terms of the Merger Agreement (the “Share Issuance Proposal”); and (ii) approve the adjournment of the Xylem Special Meeting to solicit additional proxies if a quorum is not present or if there are not sufficient votes cast at the Xylem Special Meeting to approve the Share Issuance Proposal or to ensure that any supplemental or amended disclosure, including any supplement or amendment to the enclosed joint proxy statement/prospectus, is timely provided to Xylem shareholders (the “Xylem Adjournment Proposal”). Approval of the Share Issuance Proposal requires the affirmative vote of a majority of votes cast at the Xylem Special Meeting by Xylem shareholders. Approval of the Xylem Adjournment Proposal requires the affirmative vote of holders of a majority of the Xylem Common Stock present in person or represented by proxy at the Xylem Special Meeting. Under the Indiana Business Corporation Law (the “IBCL”), virtual attendance at the Xylem Special Meeting constitutes presence in person for purposes of the vote required.

The Xylem Special Meeting will be held virtually at www.virtualshareholdermeeting.com/XYL2023SM, on May 11, 2023, at 11:00 a.m., Eastern Time. Xylem’s board of directors (the “Xylem Board”) unanimously recommends that Xylem shareholders vote “FOR” the Share Issuance Proposal.

At the Evoqua Special Meeting, Evoqua stockholders will be asked to vote on proposals to (i) adopt the Merger Agreement (the “Merger Proposal”), (ii) approve, on an advisory (non-binding) basis, the compensation that will or may be paid to Evoqua’s named executive officers in connection with the Merger (the “Advisory Compensation Proposal”) and (iii) approve the adjournment of the Evoqua Special Meeting to solicit additional proxies if there are not sufficient votes cast at the Evoqua Special Meeting to approve the Merger Proposal or to ensure that any supplemental or amended disclosure, including any supplement or amendment to the enclosed joint proxy statement/prospectus, is timely provided to Evoqua stockholders (the “Evoqua Adjournment Proposal”). If a quorum is present at the Evoqua Special Meeting, approval of the Merger Proposal requires the affirmative vote of a majority of the outstanding shares of Evoqua Common Stock entitled to vote on the proposal. If a quorum is present at the Evoqua Special Meeting, approval of the Advisory Compensation Proposal and the Evoqua Adjournment Proposal each requires the affirmative vote of the holders of a majority of the voting power of shares of Evoqua Common Stock, present in person or by proxy and entitled to vote thereon at the Evoqua Special Meeting. The chairperson of the meeting will have the right and authority to (for any or no reason) recess and/or adjourn the Evoqua Special Meeting and, if a quorum is not present, Evoqua stockholders holding a majority in voting power of shares of Evoqua Common Stock, present in person or by proxy and entitled to vote thereat, will have the power to adjourn the meeting as provided in the Third Amended and Restated Bylaws of Evoqua and the General Corporation Law of the State of Delaware. Virtual attendance by stockholders of record at the Evoqua Special Meeting constitutes presence in person for purposes of the vote required.

The Evoqua Special Meeting will be held virtually at www.virtualshareholdermeeting.com/AQUA2023SM, on May 11, 2023, at 11:00 a.m., Eastern Time. The board of directors of Evoqua (the “Evoqua Board”) unanimously recommends that Evoqua stockholders vote “FOR” the Merger Proposal, “FOR” the Advisory Compensation Proposal and “FOR” the Evoqua Adjournment Proposal.

If the Merger is consummated, at the effective time of the Merger (the “Effective Time”), each issued and outstanding share of Evoqua Common Stock as of immediately prior to the Effective Time, other than Evoqua Common Stock held in treasury by Evoqua or owned directly or indirectly by Xylem or Merger Sub, will be converted into the right to receive 0.48 shares of Xylem Common Stock (the “Exchange Ratio”), with cash paid in lieu of the issuance of fractional shares, if

The obligations of Xylem and Evoqua to consummate the Merger are subject to the satisfaction or waiver of a number of conditions set forth in the Merger Agreement, a copy of which is attached as Annex A to the enclosed joint proxy statement/prospectus. The enclosed joint proxy statement/prospectus describes the Xylem Special Meeting and the proposals to be considered thereat, the Evoqua Special Meeting and the proposals to be considered thereat, the Merger and the documents and agreements related to the Merger. It also contains or references information about Xylem and Evoqua and certain related agreements and matters. Please carefully read the entire enclosed joint proxy statement/prospectus prior to voting, including the section titled “Risk Factors” beginning on page 20 of the enclosed joint proxy statement/prospectus, for a discussion of the risks relating to the proposed Merger and the combined company. You also can obtain information about Xylem and Evoqua from documents that each has filed with the Securities and Exchange Commission. Please see the section titled “Where You Can Find More Information” beginning on page 207 of the enclosed joint proxy statement/prospectus for how you may obtain such information.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of the securities to be issued in connection with the Merger described in the enclosed joint proxy statement/prospectus or determined if the enclosed joint proxy statement/prospectus is accurate or complete. Any representation to the contrary is a criminal offense.

The enclosed joint proxy statement/prospectus is dated April 11, 2023 and is first being mailed to Xylem shareholders of record and Evoqua stockholders of record on or about April 11, 2023.

To the Shareholders of Xylem Inc.:

You are cordially invited to attend the special meeting of shareholders (the “Xylem Special Meeting”) of Xylem Inc. (“Xylem”), to be held at 11:00 a.m., Eastern Time, on May 11, 2023 virtually at www.virtualshareholdermeeting.com/XYL2023SM for the following purposes:

Xylem will transact no other business at the Xylem Special Meeting or any adjournment or postponement thereof, except such business as may be properly brought before the Xylem Special Meeting or any adjournment or postponement thereof by or at the direction of the board of directors of Xylem (the “Xylem Board”) in accordance with Xylem’s Fifth Amended and Restated Bylaws. These items of business are described in the enclosed joint proxy statement/prospectus. The Xylem Board has designated the close of business on April 5, 2023 as the record date (the “Xylem Record Date”) for the purpose of determining the holders of shares of Xylem Common Stock who are entitled to receive notice of, and to vote at, the Xylem Special Meeting and any adjournment or postponement thereof, unless a new record date is fixed in connection with any adjournment or postponement of the Xylem Special Meeting. Only holders of record of Xylem Common Stock (the “Xylem shareholders”) at the close of business on the Xylem Record Date are entitled to notice of, and to vote at, the Xylem Special Meeting and at any adjournment or postponement thereof.

The Xylem Board has unanimously (i) determined that the Merger Agreement, the merger of Merger Sub with and into Evoqua, with Evoqua surviving the merger as a direct, wholly-owned subsidiary of Xylem (the “Merger”), the Share Issuance Proposal and the other transactions contemplated by the Merger Agreement are advisable and fair to, and in the best interests of, Xylem and the Xylem shareholders, (ii) approved, authorized, adopted and declared advisable the Merger Agreement, the Merger, the Share Issuance Proposal and the other transactions contemplated by the Merger Agreement and (iii) recommended that the Xylem shareholders vote in favor of the Share Issuance Proposal. The Xylem Board recommends that the Xylem shareholders vote “FOR” the Share Issuance Proposal and “FOR” the Xylem Adjournment Proposal.

Properly executed proxy cards with no instructions indicated on the proxy card will be voted “FOR” the Share Issuance Proposal and “FOR” the Xylem Adjournment Proposal. Even if you plan to attend the Xylem Special Meeting virtually, Xylem requests that you complete, sign, date and return the enclosed proxy card in the accompanying envelope prior to the Xylem Special Meeting to ensure that your shares will be represented and voted at the Xylem Special Meeting if you later decide not to or become unable to attend virtually.

You may also submit a proxy over the Internet using the Internet address on the enclosed proxy card or by telephone using the toll-free number on the enclosed proxy card. If you submit your proxy through the Internet or by telephone, you will be asked to provide the control number from the enclosed proxy card. If you are not a shareholder of record, but instead hold your

shares in “street name” through a broker, bank, trust or other nominee, you must provide a proxy executed in your favor from your broker, bank, trust or other nominee in order to be able to vote at the Xylem Special Meeting.

Please vote as promptly as possible, whether or not you plan to attend the Xylem Special Meeting virtually. If your shares are held in the name of a broker, bank, or other nominee, please vote by following the instructions on the voting instruction form furnished by the broker, bank, or other nominee. If you hold your shares in your own name, submit a proxy to vote your shares as promptly as possible by (i) visiting the Internet site listed on the proxy card, (ii) calling the toll-free number listed on the proxy card or (iii) submitting your proxy card by mail by using the self-addressed, stamped envelope provided. Submitting a proxy will not prevent you from voting virtually, but it will help to secure a quorum and avoid added solicitation costs. Any eligible Xylem shareholder who is virtually present at the Xylem Special Meeting may vote, thereby revoking any previous proxy. In addition, a proxy may also be revoked in writing before the Xylem Special Meeting in the manner described in the enclosed joint proxy statement/prospectus.

The enclosed joint proxy statement/prospectus provides a detailed description of the Merger, the Merger Agreement and the other matters to be considered at the Xylem Special Meeting. We urge you to read carefully the enclosed joint proxy statement/prospectus—including any documents incorporated by reference therein—and the annexes in their entirety. If you have any questions concerning the Merger or the enclosed joint proxy statement/prospectus, would like additional copies or need help voting your shares of Xylem Common Stock, please contact Innisfree M&A Incorporated:

To the Stockholders of Evoqua Water Technologies Corp.:

You are cordially invited to attend the special meeting of stockholders (the “Evoqua Special Meeting”) of Evoqua Water Technologies Corp. (“Evoqua”) virtually, to be held at 11:00 a.m., Eastern Time, on May 11, 2023 at www.virtualshareholdermeeting.com/AQUA2023SM, for the following purposes:

Evoqua will transact no other business at the Evoqua Special Meeting or any adjournment or postponement thereof, except such business as may properly be brought before the Evoqua Special Meeting or any adjournment or postponement thereof in accordance with the Third Amended and Restated Bylaws of Evoqua (the “Evoqua Bylaws”). The enclosed joint proxy statement/prospectus, of which this notice is a part, describes the proposals listed above in more detail. Please refer to the attached documents, including the Merger Agreement and all other annexes and any documents incorporated by reference, for further information with respect to the business to be transacted at the Evoqua Special Meeting. You are encouraged to read the entire document carefully before voting. In particular, please see the sections titled “The Merger” beginning on page 66 of the enclosed joint proxy statement/prospectus for a description of the transactions contemplated by the Merger Agreement and “Risk Factors” beginning on page 20 of the enclosed joint proxy statement/prospectus for an explanation of the risks associated with the Merger and the other transactions contemplated by the Merger Agreement.

If a quorum is present at the Evoqua Special Meeting, approval of the Merger Proposal by the affirmative vote of the holders of a majority of the outstanding shares of Evoqua common stock, par value $0.01 per share (“Evoqua Common Stock”), entitled to vote on the proposal is required to consummate the merger of Merger Sub with and into Evoqua, with Evoqua surviving the merger as a direct, wholly-owned subsidiary of Xylem, as contemplated by the Merger Agreement (the “Merger”). Holders of Evoqua Common Stock (“Evoqua stockholders”) will also be asked to approve the Advisory Compensation Proposal and the Evoqua Adjournment Proposal. If a quorum is present at the Evoqua Special Meeting, approval of the Advisory Compensation Proposal and the Evoqua Adjournment Proposal each requires the affirmative vote of the holders of a majority of the voting power of shares of Evoqua Common Stock present in person or represented by proxy and entitled to vote thereon at the Evoqua Special Meeting. The chairperson of the meeting will have the right and authority to (for any or no reason) recess and/or adjourn the Evoqua Special Meeting and, if a quorum is not present at the Evoqua Special Meeting, Evoqua stockholders holding a majority in voting power of shares of Evoqua Common Stock, present in person or by proxy and entitled to vote thereat, will have the power to adjourn the meeting as provided in the Evoqua Bylaws and the General Corporation Law of the State of Delaware. In addition, the Evoqua Special Meeting may be postponed, rescheduled or canceled by the Evoqua board of directors (the “Evoqua Board”) in its discretion. For additional information regarding the conduct of the Evoqua Special Meeting, please see the section titled “Evoqua Special Meeting” beginning on page 57 of the enclosed joint proxy statement/prospectus.

The Evoqua Board has fixed the close of business on April 5, 2023, as the record date (the “Evoqua Record Date”) for the determination of the Evoqua stockholders entitled to receive notice of, and to vote at, the Evoqua Special Meeting or any adjournment or postponement thereof. The Evoqua stockholders of record as of the close of business on the Evoqua Record Date are the only Evoqua stockholders who are entitled to receive notice of, and to vote at, the Evoqua Special Meeting and any adjournment or postponement thereof unless a new record date is fixed in connection with any adjournment or postponement of the Evoqua Special Meeting. A list of Evoqua stockholders entitled to vote at the Evoqua Special Meeting as of the Evoqua Record Date will be open to the examination of any Evoqua stockholder for any legally valid purpose at Evoqua’s principal executive offices for a period of 10 days prior to the Evoqua Special Meeting. The list of eligible Evoqua stockholders of record also will be available for inspection during the Evoqua Special Meeting at www.virtualshareholdermeeting.com/AQUA2023SM by entering the 16-digit control number provided on your proxy card or voting instruction form and completing the required online attestation form. For additional information regarding the Evoqua Special Meeting, see the section titled “Evoqua Special Meeting” beginning on page 57 of the enclosed joint proxy statement/prospectus.

The Evoqua Board, at a meeting duly called and held, has by unanimous vote (i) determined that the Merger Agreement, the Merger and the other transactions contemplated by the Merger Agreement are fair and in the best interest of, and are advisable to, Evoqua and the Evoqua stockholders, (ii) approved and adopted the Merger Agreement and approved the Merger and the other transactions contemplated by the Merger Agreement and (iii) recommended that the Evoqua stockholders approve the Merger Agreement. The Evoqua Board unanimously recommends that Evoqua stockholders vote “FOR” the Merger Proposal, “FOR” the Advisory Compensation Proposal and “FOR” the Evoqua Adjournment Proposal.

Properly executed proxy cards with no instructions indicated on the proxy card will be voted “FOR” the Merger Proposal, “FOR” the Advisory Compensation Proposal and “FOR” the Evoqua Adjournment Proposal. Even if you plan to attend the Evoqua Special Meeting, Evoqua requests that you complete, sign, date and return the enclosed proxy card in the accompanying envelope prior to the Evoqua Special Meeting to ensure that your shares will be represented and voted at the Evoqua Special Meeting if you later decide not to or are unable to attend.

You may also submit a proxy over the Internet using the Internet address on the enclosed proxy card or by telephone using the toll-free number on the enclosed proxy card. If you submit your proxy through the Internet or by telephone, you will be asked to provide the control number from the enclosed proxy card. If you are not a stockholder of record, but instead hold your shares in “street name” through a broker, bank, trustee or other nominee, you must provide a proxy executed in your favor from your broker, bank, trustee or other nominee in order to be able to vote at the Evoqua Special Meeting.

Please vote as promptly as possible, whether or not you plan to attend the Evoqua Special Meeting. If your shares are held in the name of a broker, bank or other nominee, please vote by following the instructions on the voting instruction form furnished by the broker, bank or other nominee. If you hold your shares in your own name, submit a proxy to vote your shares as promptly as possible by (i) visiting the Internet site listed on the proxy card, (ii) calling the toll-free number listed on the proxy card or (iii) submitting your proxy card by mail by using the self-addressed, stamped envelope provided. Submitting a proxy will not prevent you from voting, but it will help to secure a quorum and avoid added solicitation costs. Any eligible Evoqua stockholder entitled to vote and who is virtually present at the Evoqua Special Meeting may vote, thereby revoking any previous proxy. In addition, a proxy may also be revoked in writing before the Evoqua Special Meeting in the manner described in the enclosed joint proxy statement/prospectus.

The enclosed joint proxy statement/prospectus provides a detailed description of the Merger, the Merger Agreement and the other matters to be considered at the Evoqua Special Meeting. We urge you to read carefully the enclosed joint proxy statement/prospectus—including any documents incorporated by reference—and the annexes in their entirety. If you have any questions concerning the Merger Proposal, the Advisory Compensation Proposal, the Evoqua Adjournment Proposal, the Merger or the enclosed joint proxy statement/prospectus, would like additional copies, or need help voting your shares of Evoqua Common Stock, please contact:

This document, which forms part of a registration statement on Form S-4 filed with the U.S. Securities and Exchange Commission (the “SEC”) by Xylem Inc., an Indiana corporation (“Xylem”), constitutes a prospectus of Xylem under Section 5 of the Securities Act of 1933 (as amended, the “Securities Act”) with respect to the shares of Xylem common stock, par value $0.01 per share (“Xylem Common Stock”) to be issued to the stockholders of Evoqua Water Technologies Corp., a Delaware corporation (“Evoqua”), pursuant to the Agreement and Plan of Merger, dated as of January 22, 2023 (as amended from time to time, the “Merger Agreement”) by and among Xylem, Fore Merger Sub, Inc., a Delaware corporation and a direct, wholly-owned subsidiary of Xylem (“Merger Sub”) and Evoqua. This document also constitutes a proxy statement of each of Xylem and Evoqua under Section 14(a) of the Securities Exchange Act of 1934 (as amended, the “Exchange Act”) and a notice of meeting with respect to the special meeting of Evoqua stockholders (the “Evoqua Special Meeting”) and the special meeting of Xylem shareholders (the “Xylem Special Meeting”).

You should rely only on the information contained in or incorporated by reference into this joint proxy statement/prospectus. Neither Xylem nor Evoqua have authorized anyone to provide you with information that is different from, or in addition to, that contained in or incorporated by reference into this joint proxy statement/prospectus. This joint proxy statement/prospectus is dated April 11, 2023. The information contained in this joint proxy statement/prospectus is accurate only as of that date or, in the case of information in a document incorporated by reference, as of the date of such document, unless the information specifically indicates that another date applies. Neither the mailing of this joint proxy statement/prospectus to Xylem shareholders and Evoqua stockholders nor the issuance by Xylem of Xylem Common Stock pursuant to the Merger Agreement will create any implication to the contrary.

This joint proxy statement/prospectus does not constitute an offer to sell, or a solicitation of an offer to buy, any securities, or the solicitation of a proxy, in any jurisdiction to or from any person to whom it is unlawful to make any such offer or solicitation in such jurisdiction. Xylem has supplied all information contained in this joint proxy statement/prospectus relating to Xylem, and Evoqua has supplied all such information relating to Evoqua. Xylem and Evoqua have both contributed to the information related to the Merger (as defined in the section titled “Questions and Answers” beginning on page vii of this joint proxy statement/prospectus) contained in this joint proxy statement/prospectus.

Unless the context otherwise requires, all references in this joint proxy statement/prospectus to “Xylem” refer to Xylem Inc., an Indiana corporation. Unless the context otherwise requires, all references in this joint proxy statement/prospectus to “Evoqua” refer to Evoqua Water Technologies Corp., a Delaware corporation. All references in this joint proxy statement/prospectus to “Xylem Common Stock” refer to the common stock of Xylem, par value $0.01 per share, and all references in this joint proxy statement/prospectus to “Evoqua Common Stock” refer to the common stock of Evoqua, par value $0.01 per share. All references in this joint proxy statement/prospectus to “Xylem shareholders” refer to the holders of Xylem Common Stock, and all references in this joint proxy statement to “Evoqua stockholders” refer to the holders of Evoqua Common Stock. All references in this joint proxy statement/prospectus to “Merger Agreement” refer to the Agreement and Plan of Merger, dated as of January 22, 2023, by and among Xylem, Merger Sub and Evoqua, as it may be amended from time to time, a copy of which is attached as Annex A to this joint proxy statement/prospectus and incorporated by reference herein. All references in this joint proxy statement/prospectus to the “Exchange Ratio” refer to the ratio of 0.48 shares of Xylem Common Stock per outstanding share of Evoqua Common Stock that will be issued to Evoqua stockholders in connection with the Merger.

This joint proxy statement/prospectus incorporates by reference important business and financial information about Xylem and Evoqua from other documents that are not included in or delivered with this joint proxy statement/prospectus. For a listing of the documents incorporated by reference into this joint proxy statement/prospectus, see the section titled “Where You Can Find More Information” beginning on page 207 of this joint proxy statement/prospectus.

You may request copies of this joint proxy statement/prospectus and any of the documents incorporated by reference herein or other information concerning Xylem or Evoqua, without charge, upon written or oral request to the applicable company’s principal executive offices. The respective addresses and phone numbers of such principal executive offices are listed below.

If you would like to request any of the Xylem or Evoqua documents that are incorporated by reference into this joint proxy statement/prospectus, please do so by May 4, 2023 in order to receive them before the Xylem Special Meeting and the Evoqua Special Meeting.

You may also obtain any of the documents incorporated by reference into this joint proxy statement/prospectus without charge through the SEC’s website at www.sec.gov. In addition, you may obtain copies of documents filed by Xylem with the SEC by accessing Xylem’s website at https://xylem.com/en-us/investors/financial information. You may also obtain copies of documents filed by Evoqua with the SEC by accessing Evoqua’s website at https://aqua.evoqua.com/financials/sec-filings/default.aspx.

We are not incorporating the contents of the websites of the SEC, Xylem, Evoqua or any other entity into this joint proxy statement/prospectus. We are providing the information about how you can obtain certain documents that are incorporated by reference into this joint proxy statement/prospectus at these websites only for your convenience.

For a more detailed description of the information incorporated by reference in this joint proxy statement/prospectus and how you may obtain it, see the section titled “Where You Can Find More Information” beginning on page 207 of this joint proxy statement/prospectus.

In addition, if you have questions about the Merger or this joint proxy statement/prospectus or need to obtain proxy cards or other information related to the proxy solicitation, contact Innisfree M&A Incorporated, the proxy solicitor for Xylem, toll-free at (877) 456-3422 or, for brokers and banks, collect at (212) 750-5833, or Okapi Partners LLC, the proxy solicitor for Evoqua, toll-free at (877) 259-6290 or, for brokers and banks, at (212) 297-0720. You will not be charged for any of these documents that you request.

The following questions and answers briefly address some commonly asked questions about the Evoqua Special Meeting, the Xylem Special Meeting and the Merger. They may not include all the information that is important to Evoqua stockholders and Xylem shareholders. Evoqua stockholders and Xylem shareholders should carefully read this entire joint proxy statement/prospectus, including the annexes and the other documents referred to herein.

In deciding how to vote on the proposals to be considered and voted on at the Xylem Special Meeting and the Evoqua Special Meeting, Xylem shareholders and Evoqua stockholders should carefully consider the following risk factors and all of the information contained in this joint proxy statement/prospectus or incorporated by reference in this joint proxy statement/prospectus, including, but not limited to, the matters addressed in the section titled “Cautionary Statement Regarding Forward-Looking Statements” beginning on page 47 of this joint proxy statement/prospectus and particularly the risk factors contained in Xylem’s and Evoqua’s other filings with the SEC incorporated herein by reference. See the section titled “Where You Can Find More Information” beginning on page 207 of this joint proxy statement/prospectus.

The consummation of the Merger is subject to several customary conditions to Closing and there can be no assurance that such conditions to Closing that remain outstanding will be satisfied or waived (to the extent permitted by law). The failure to timely satisfy the required conditions could delay the consummation of the Merger for a significant period of time or prevent the consummation of the Merger from occurring at all. These conditions to Closing include, among others: (i) obtaining the Evoqua Stockholder Approval; (ii) obtaining the Xylem Shareholder Approval; (iii) (a) the expiration or earlier termination of any applicable waiting period under the HSR Act or any other Antitrust Laws, (b) the receipt of, making of or expiration or earlier termination of any applicable waiting period of the other antitrust, competition, investment, trade regulation or similar consents, authorizations, orders or approvals, in each case, that are required under certain Antitrust Laws set forth in Evoqua’s disclosure letter to the Merger Agreement will have been obtained and (c) receipt of, making of or expiration or earlier termination of any applicable waiting period of any consents, authorizations, orders or approvals, in each case, that are required under any foreign investment law, the absence of which would prohibit the consummation of the Merger and the other transactions contemplated by the Merger Agreement, including in certain jurisdictions agreed to by the parties as set forth in Evoqua’s disclosure letter to the Merger Agreement; (iv) no governmental authority or court of competent jurisdiction has issued a temporary restraining order, preliminary or permanent injunction or other judgment, order or decree, and no other legal restraint or prohibition will be in effect, and no law will have been enacted, entered, promulgated, enforced or deemed applicable by any governmental entity that, in any such case, prohibits or makes illegal the consummation of the Merger; (v) the NYSE having approved the listing of the shares of Xylem Common Stock to be issued in the Merger, subject to official notice of issuance; (vi) the registration statement on Form S-4, of which this joint proxy statement/prospectus forms a part, having been declared effective by the SEC under the Securities Act and no stop order suspending the effectiveness being in effect, and no proceedings for that purpose having been initiated or threatened; (vii) subject to specified materiality standards, the accuracy of certain representations and warranties of the parties; (viii) compliance by the parties in all material respects with their respective obligations under the Merger Agreement; (ix) the delivery of an officer’s closing certificate by each of Evoqua and Xylem; (x) the absence of a Material Adverse Effect with respect to each of Xylem and Evoqua; and (xi) the receipt by Evoqua of the Closing Tax Opinion.

Many of the conditions to consummation of the Merger are not within either Evoqua’s or Xylem’s control, and neither Evoqua nor Xylem can predict when, or if, these conditions will be satisfied. There can be no assurance as to when, or if, the conditions to Closing will be satisfied or waived or that other events will not intervene to delay or result in the termination of the Merger. If any of these conditions are not satisfied or waived prior to the Outside Date, it is possible that the Merger Agreement may be terminated. See the section titled “The Merger Agreement—Termination” beginning on page 168 of this joint proxy statement/prospectus for more information on the circumstances under which the Merger Agreement may be terminated. Although Evoqua and Xylem have agreed in the Merger Agreement to use reasonable best efforts to consummate the Merger in the most expeditious manner practicable, including to obtain certain governmental and regulatory clearances and approvals, subject to certain limitations (including that Xylem will not be required to make divestitures or commit to certain other remedies that would have or would reasonably be expected to have, individually or in the aggregate, a material impact on (i) Evoqua and its subsidiaries (taken as a whole) or Xylem and its subsidiaries (taken as a whole, but assuming Xylem and its subsidiaries are the same size as Evoqua and its subsidiaries) or (ii) the reasonably expected benefits of the Merger), these and other conditions to Closing may fail to be satisfied. See the section titled “The Merger Agreement—Covenants—Regulatory Approvals; Consents” beginning on page 151 of this joint proxy statement/prospectus for more information regarding the obligations of the parties to consummate the Merger and obtain regulatory approvals. In addition, satisfying the conditions to and consummating the Merger may take longer, and could cost more, than Evoqua and Xylem expect. Neither Evoqua nor Xylem can predict whether and when these other conditions will be satisfied. Furthermore, the requirements for obtaining the required clearances and approvals could delay the consummation of the Merger for a significant period of time or prevent the

consummation of the Merger. Any delay in consummating the Merger may adversely affect the cost savings and other benefits that Evoqua and Xylem expect to achieve if the Merger and the integration of the companies’ respective businesses are not consummated within the expected timeframe. There can be no assurance that all required regulatory approvals will be obtained or applicable waiting periods will have expired or been terminated prior to the Outside Date, or at all. The governmental agencies from which the parties have sought or are seeking certain approvals in connection with the Merger have broad discretion in administering applicable governing regulations, and may impose requirements, limitations or costs, require divestitures or place restrictions on the conduct of the combined company’s business after the Closing. Such requirements, limitations, costs, divestitures or restrictions could delay or prevent the consummation of the Merger or have a material adverse effect on the combined company’s business and results of operations. Even after the expiration of the waiting period under the HSR Act or other applicable Antitrust Laws, the United States Federal Trade Commission (“FTC”) or the United States Department of Justice (“DOJ”) or other applicable antitrust regulators could take action under the Antitrust Laws to prevent or unwind the Merger, require the divestiture of assets, impose conditions on the consummation of the Merger or require changes to the terms of the Merger or Merger Agreement. Additionally, state attorneys general could seek to block or challenge the Merger as they deem necessary or desirable in the public interest at any time, including after consummation of the Merger. In addition, in some circumstances, a third party could initiate a private action under the Antitrust Laws challenging or seeking to enjoin the Merger, before or after it is consummated.

See the section titled “The Merger Agreement—Conditions Precedent” beginning on page 166 of this joint proxy statement/prospectus for a more detailed description of these closing conditions.

If the Merger is not consummated for any reason, including because Xylem shareholders fail to approve the Share Issuance Proposal or because Evoqua stockholders fail to approve the Merger Proposal, the ongoing businesses and financial results of Evoqua and Xylem may be adversely affected and, without realizing any of the potential benefits of having consummated the Merger, each of Evoqua and Xylem may experience certain negative effects, including the following:

If the Merger is not consummated, these risks may materialize and may materially and adversely affect Evoqua’s and Xylem’s respective businesses, operations, financial results and share prices.

The Merger Agreement restricts Evoqua and Xylem from taking specified actions without the consent of the other party prior to the Effective Time. The Merger Agreement obligates each of Evoqua and Xylem to generally use their respective reasonable best efforts to carry on their respective businesses in all material respects in the ordinary course of business

consistent with past practice until the Effective Time and to use their respective reasonable best efforts to (i) preserve their respective business organizations and assets, (ii) keep available the services of their respective current officers and key employees and consultants and (iii) preserve their respective goodwill and relationships with customers, suppliers, licensors, licensees, distributors and others having material business dealings with such party. These restrictions could prevent Evoqua or Xylem from pursuing certain attractive business opportunities that arise prior to the Effective Time, executing on their respective business strategies and attaining financial goals.

See the section titled “The Merger Agreement—Covenants—Conduct of Business” beginning on page 147 of this joint proxy statement/prospectus for a more detailed description of these restrictions.

Under the DGCL with respect to Evoqua stockholders, and under the IBCL with respect to Xylem shareholders, neither the Evoqua stockholders nor the Xylem shareholders are entitled to appraisal rights in connection with the Merger. See the section titled “The Merger—No Appraisal Rights” beginning on page 137 of this joint proxy statement/prospectus.

Under the Merger Agreement, each of Evoqua and Xylem is subject to certain restrictions on its ability to solicit alternative business combination proposals from third parties or, subject to certain exceptions relating to the exercise of fiduciary duties by the Evoqua Board or the Xylem Board, as applicable, participate in discussions or negotiations with respect to such proposals or provide information in connection with such proposals. Evoqua and Xylem may terminate the Merger Agreement and enter into an agreement providing for an Evoqua Superior Proposal or Xylem Superior Proposal, respectively, only if specified conditions have been satisfied, and such a termination would result in Xylem being required to pay to Evoqua the Xylem Termination Fee or Evoqua being required to pay to Xylem the Evoqua Termination Fee, as applicable. If the Merger Agreement is terminated and Evoqua or Xylem determines to seek another business combination, such party may not be able to negotiate a transaction with another party on terms comparable to, or better than, the terms of the Merger. While Evoqua and Xylem believe these provisions and agreements are reasonable and customary and are not preclusive of other offers, these provisions and the associated termination fees could discourage a third party that may have an interest in acquiring all or a significant part of Evoqua or Xylem from considering or proposing such acquisition, even if such third party were prepared to pay consideration with a higher value than the Merger Consideration. These provisions might also result in a potential third-party acquirer proposing to pay a lower price than it might otherwise have proposed to pay because of the added expense of a termination fee that may become payable in certain circumstances.

See the sections titled The Merger Agreement—Covenants—No Solicitation,” “The Merger Agreement—Termination” and “The Merger Agreement—Termination Fee” beginning on pages 154, 168 and 170 of this joint proxy statement/prospectus, respectively.

Each of Evoqua and Xylem may in certain circumstances terminate the Merger Agreement to enter into an agreement providing for an Evoqua Superior Proposal or Xylem Superior Proposal, respectively, prior to obtaining the Xylem Shareholder Approval or Evoqua Stockholder Approval, respectively. In such event, Xylem would be obligated to pay to Evoqua the Xylem Termination Fee or Evoqua would be obligated to pay to Xylem the Evoqua Termination Fee, as applicable, but such party would have no further material obligations or liabilities to the other relating to or arising out of the Merger Agreement or the Merger. Such termination would deny the other party and its stockholders or shareholders (as applicable) any benefits from the Merger and could materially and negatively impact the other party’s share price.

See the sections titled “The Merger Agreement—Covenants—No Solicitation,” “The Merger Agreement—Covenants—No Change of Recommendation,” “The Merger Agreement—Termination” and “The Merger Agreement—Termination Fee” beginning on pages 154, 157, 168 and 170 of this joint proxy statement/prospectus, respectively.

Upon consummation of the Merger, each share of Evoqua Common Stock issued and outstanding immediately prior to the Effective Time, other than Evoqua Common Stock held in treasury by Evoqua or owned directly or indirectly by Xylem or Merger Sub, will be converted into the right to receive 0.48 shares of Xylem Common Stock. Because the Exchange Ratio is

fixed and will only be adjusted in certain limited circumstances (including stock splits or stock dividends, reorganization, recapitalization or other like change with respect to Evoqua Common Stock or Xylem Common Stock), any changes in the market value of shares of Evoqua Common Stock or Xylem Common Stock may affect the value that Evoqua stockholders will be entitled to receive upon consummation of the Merger. Share price changes may result from a variety of factors, including changes in the business, operations or prospects of Evoqua or Xylem or their competitors, market assessments of the likelihood that the Merger will be consummated, the timing of the Merger and receipt of required regulatory approvals, regulatory considerations, interest rates, general market and economic conditions and other factors. Such factors are difficult to predict and in many cases may be beyond the control of Evoqua and Xylem. Consequently, at the time of the Evoqua Special Meeting the Evoqua stockholders will not know the actual market value of the Merger Consideration they will receive for each of their shares of Evoqua Common Stock when the Merger is consummated. Similarly, Xylem shareholders will not know or be able to determine at the time of the Xylem Special Meeting the market value of the shares of Xylem Common Stock to be issued pursuant to the Merger Agreement compared to the market value of the shares of Evoqua Common Stock that are being exchanged in the Merger. You are urged to obtain current market quotations for Evoqua Common Stock and Xylem Common Stock in determining whether to vote in favor of the Share Issuance Proposal, in the case of Xylem shareholders, or the Merger Proposal, in the case of Evoqua stockholders.

Uncertainty about the effect of the Merger on Evoqua’s and Xylem’s employees, customers, distributors, suppliers, vendors and other business partners may have an adverse effect on Evoqua and Xylem. These uncertainties may impair each company’s ability to attract, retain and motivate key personnel until the Merger is consummated and for a period thereafter, and the attention of each of Evoqua and Xylem management may be directed to Merger-related considerations and may be diverted from the day-to-day operations. No assurance can be given that the combined company will be able to attract, hire, retain and motivate key personnel and other employees of Evoqua and Xylem to the same extent that Evoqua and Xylem have been able to attract, hire, retain and motivate key personnel and other employees in the past. If, despite their retention efforts, key employees of Evoqua or Xylem depart because of issues relating to the uncertainty about their future roles and difficulty of integration or a desire not to remain with the combined company, the combined company’s (or, if the Merger is not consummated, Evoqua’s or Xylem’s) business could be harmed and its ability to realize the anticipated benefits of the Merger could be adversely affected. Evoqua and Xylem may not be able to locate suitable replacements for key employees that leave either company or offer employment to potential replacements on reasonable terms. In addition, there could be disruptions to or distractions for the workforce and management, including disruptions associated with integrating employees into the combined company. Parties with which Evoqua and Xylem do business may experience uncertainty associated with the Merger, including with respect to current or future business relationships with Evoqua and Xylem. Evoqua’s and Xylem’s respective business relationships may be subject to disruption as customers, distributors, suppliers, vendors and other business partners that deal with Evoqua or Xylem may attempt to renegotiate changes in existing business relationships or consider entering into alternative relationships with third parties other than Evoqua and Xylem. These disruptions could have an adverse effect on the businesses, financial condition, results of operations or prospects of Evoqua and Xylem, including an adverse effect on the anticipated benefits of the Merger. The risk and adverse effect of such disruptions could be exacerbated by a delay in consummation of the Merger or the termination of the Merger Agreement. Further, any disruption to Evoqua’s or Xylem’s business resulting from the announcement and pendency of the Merger, including any adverse impact in relationships with employees, customers, distributors, suppliers, vendors and other business partners could continue or accelerate in the event of a failure to consummate the Merger.

Certain contracts entered into by Evoqua contain change in control or other provisions that may be triggered as a result of the Merger. If the counterparties to such agreements do not consent to the Merger or waive such provisions, the counterparties may have the ability to exercise certain rights (including termination rights), resulting in the combined company incurring liabilities as a consequence of breaching such agreements, or causing the combined company to lose the benefit of such agreements or incur costs in seeking replacement agreements. Even if Evoqua and Xylem are able to obtain consents or negotiate waivers, the counterparties may require consideration for granting such consents or waivers or seek to renegotiate the agreements on terms less favorable to Evoqua and the combined company.

Evoqua and Xylem entered into the Merger Agreement with the expectation that the Merger will result in various benefits and cost savings from combining the Evoqua and Xylem businesses. Achieving the anticipated benefits of the Merger is subject

to several uncertainties, including whether the businesses of Evoqua and Xylem can be integrated in an efficient and effective manner. Failure to achieve these anticipated benefits could result in increased costs or decreases in the amount of expected revenues and cost savings from the Merger and could adversely affect the combined company’s future business, financial condition, operating results and cash flows.

The Merger involves numerous operational, strategic, financial, accounting, legal, tax and other functions that must be integrated, as well as integrating relationships with customers, vendors and business partners. Evoqua and Xylem may be unable to successfully integrate their respective operations. Failure to successfully integrate the businesses of Evoqua and Xylem in the expected timeframe may adversely affect the future results of the combined company, and, consequently, the value of the Xylem Common Stock that Evoqua stockholders will receive as the Merger Consideration.

It is possible that the integration process could take longer than anticipated, could give rise to unanticipated costs and delays or performance shortfalls and could result in the loss of valuable employees, the disruption of each of Evoqua’s and Xylem’s ongoing businesses, processes and systems or inconsistencies in standards, controls, procedures, practices, policies and compensation arrangements, any of which could adversely affect the combined company’s ability to achieve the anticipated benefits of the Merger. The combined company’s results of operations could also be adversely affected by any issues attributable to either company’s operations that arise or are based on events or actions that occur prior to the consummation of the Merger. Evoqua and Xylem may have difficulty addressing possible differences in corporate cultures and management philosophies. The integration process is subject to several uncertainties, and no assurance can be given that the anticipated benefits will be realized or, if realized, the timing of their realization.

Upon the consummation of the Merger, Evoqua stockholders will no longer be stockholders of Evoqua. Instead, former Evoqua stockholders will become Xylem shareholders and their rights as Xylem shareholders will be governed by the laws of the State of Indiana, and subject to and governed by the terms of the Fourth Amended and Restated Articles of Incorporation of Xylem (the “Xylem Charter”) and the Xylem Bylaws. The terms of the Xylem Charter and the Xylem Bylaws are in some respects different than the terms of the Amended and Restated Certificate of Incorporation of Evoqua (the “Evoqua Charter”) and the Evoqua Bylaws, respectively, which currently govern the rights of Evoqua stockholders. See the section titled “Comparison of Stockholders’ and Shareholders’ Rights” beginning on page 179 of this joint proxy statement/prospectus for a discussion of these rights.

On March 13, 2023, a purported Evoqua stockholder filed the O’Dell Action. The O’Dell Action generally alleges that Evoqua and the Evoqua Board violated federal securities laws, including Sections 14(a) and 20(a) of the Exchange Act and Rule 14a-9 promulgated under the Exchange Act, by issuing a materially incomplete and misleading registration statement on Form S-4. The plaintiff in the O’Dell Action seeks, among other things, to enjoin the transactions contemplated by the Merger Agreement and an award of attorneys’ and expert fees and expenses. Additional lawsuits in connection with the Merger may be filed in the future. Even if such legal proceedings are without merit, defending against these claims can be time consuming, result in substantial costs and divert management time and resources away from their regular businesses. There can be no assurance that any of the defendants will be successful in defending current or any potential future legal proceedings. An adverse judgment could result in monetary damages, which could have a negative impact on Evoqua’s and Xylem’s respective liquidity and financial condition. One of the conditions to the consummation of the Merger is that no temporary restraining order, preliminary or permanent injunction or other judgment, order or decree issued by any court of competent jurisdiction or other legal restraint or prohibition will be in effect. As such, if a plaintiff is successful in obtaining an injunction prohibiting consummation of the Merger, such injunction may delay or prevent the Merger from being consummated, or from being consummated within the expected timeframe, which may adversely affect Evoqua’s or Xylem’s respective business, financial position and results of operations. The existence of litigation relating to the Merger could also impact the likelihood of obtaining the Evoqua Stockholder Approval or the Xylem Shareholder Approval.

See the section titled “The Merger—Litigation Relating to the Merger” beginning on page 138 of this joint proxy statement/prospectus.

Evoqua and Xylem have each incurred, and will continue to incur, non-recurring transaction-related costs associated with consummating the Merger, combining the operations of the two organizations and achieving the desired benefits of the Merger.

These costs, expenses, and fees have been, and will continue to be, significant. Non-recurring transaction costs include, or may include, but are not limited to, fees paid to legal, financial, accounting and other advisors or business consultants, fees paid to proxy solicitors, retention, severance, change in control and other integration-related costs, filing fees and printing costs. Additional unanticipated costs may be incurred in the Merger and the integration of the businesses of Evoqua and Xylem. There can be no assurance that the integration process will deliver all or substantially all of the benefits of the Merger in the near term, the long term or at all. The costs described above and any unanticipated costs and expenses, many of which will be payable by Evoqua or Xylem regardless of whether or not the Merger is consummated, could have an adverse effect on Evoqua’s or Xylem’s financial condition and operating results and may exceed the costs historically borne by Evoqua and Xylem as separate companies.

Evoqua’s directors and executive officers have interests in the Merger that may be different from, or in addition to, the interests of Evoqua stockholders generally. The interests of Evoqua’s directors and executive officers include, among others, severance rights, vesting protections for equity awards in the event of termination of employment in connection with a change in control, rights to continuing indemnification and directors’ and officers’ liability insurance. See the section titled “The Merger—Interests of Evoqua’s Directors and Executive Officers in the Merger” beginning on page 125 of this joint proxy statement/prospectus for a more detailed description of these interests. In addition, Xylem has agreed to appoint two current members of the Evoqua Board, who will be selected by the Evoqua Board and consented to by the Xylem Board effective as of the Closing. Evoqua stockholders should be aware of these interests when they consider the recommendations of the Evoqua Board that they vote to approve the Merger Proposal. Evoqua’s Board was aware of and considered the interests of Evoqua’s respective directors and officers, among other matters, in evaluating the terms and structure, and overseeing the negotiation of the Merger, in approving the Merger Agreement, the Merger and the other transactions contemplated thereby, and the recommendation of the Evoqua Board that the Evoqua stockholders adopt the Merger Agreement.

To the extent permitted by law, Evoqua or Xylem may determine to waive, in whole or part, one or more of the conditions to their respective obligations to consummate the Merger. If such a situation arises, Evoqua and Xylem currently expect to evaluate the materiality of any proposed waiver and its effect on Evoqua stockholders or Xylem shareholders, as applicable, in light of the facts and circumstances at the time to determine whether any amendment of this joint proxy statement/prospectus or any re-solicitation of proxies is required or warranted in light of such waiver. In some cases, if the Evoqua Board or the Xylem Board, as applicable, determines that such a waiver is warranted, but that such waiver or its effect on Evoqua stockholders or Xylem shareholders, respectively, is not sufficiently material to warrant re-solicitation of proxies, the Evoqua Board and the Xylem Board, as applicable, have the discretion to consummate the Merger and the issuance of Xylem Common Stock without seeking further approval from Evoqua stockholders or Xylem shareholders, respectively. Any determination as to whether to waive any condition to the Merger, and as to whether to re-solicit Evoqua Stockholder Approval or Xylem Shareholder Approval or amend this joint proxy statement/prospectus as a result of such waiver, will be made by Evoqua or Xylem, as applicable, at the time of such waiver based on the facts and circumstances as they exist at that time.

The Merger may be less accretive than expected, or may be dilutive, to Xylem’s earnings per share. Future events and conditions could decrease or delay any accretion, result in dilution, or cause greater dilution than is currently expected, including adverse changes in market conditions, operating results, competitive conditions, laws and regulations affecting the water and wastewater treatment business, capital expenditure obligations, higher than expected integration costs, lower than expected synergies and general economic conditions.

The unaudited pro forma condensed combined financial information and unaudited forecasted financial information included in this joint proxy statement/prospectus is presented for illustrative purposes only, contains a variety of adjustments, assumptions and preliminary estimates and does not represent the actual financial position or results of operations of Evoqua

and Xylem prior to the Merger or that of the combined company following the Merger for several reasons. See the section titled “Unaudited Pro Forma Condensed Combined Financial Information” beginning on page 32 of this joint proxy statement/prospectus for a more detailed description of the unaudited pro forma condensed combined financial information and see section titled “The Merger—Certain Unaudited Forecasted Financial Information” beginning on page 118 of this joint proxy statement/prospectus. In addition, the Merger and post-Merger integration process may give rise to unexpected liabilities and costs, including costs associated with potential transaction-related litigation or other claims. Unexpected delays in consummating the Merger or in connection with the post-Merger integration process may significantly increase the related costs and expenses incurred by Xylem. The actual financial positions and results of operations of Evoqua and Xylem prior to the Merger and that of the combined company following the Merger may be different, possibly materially, from the unaudited pro forma condensed combined financial information or unaudited forecasted financial information included in this joint proxy statement/prospectus. In addition, the assumptions used in preparing the unaudited pro forma condensed combined financial information and unaudited forecasted financial information included in this joint proxy statement/prospectus may not prove to be accurate and may be affected by other factors. Any significant changes in the market value of Xylem Common Stock may cause a significant change in the purchase price used for Xylem’s accounting purposes and the unaudited pro forma condensed combined financial information included in this joint proxy statement/prospectus.

In connection with the signing of the Merger Agreement, (i) the Evoqua Board received (a) a written opinion from Goldman Sachs regarding the fairness, from a financial point of view, of the Exchange Ratio to Evoqua stockholders (other than Xylem and its affiliates), and (b) a written opinion from BofA Securities regarding the fairness, from a financial point of view, of the Exchange Ratio to Evoqua Stockholders (other than holders of Excluded Shares), and (ii) the Xylem Board received opinions from Lazard and Guggenheim Securities, which were delivered orally on January 21, 2023, and subsequently confirmed in written opinions dated January 22, 2023, regarding the fairness, from a financial point of view, of the Exchange Ratio to Xylem shareholders. Evoqua and Xylem have not requested or obtained updated opinions from their respective financial advisors as of the date of this joint proxy statement/prospectus, nor do they anticipate requesting or obtaining updated opinions in the future, including as of the Closing. Changes in the operations and prospects of Evoqua or Xylem, general market and economic conditions and other factors that may be beyond the control of Evoqua or Xylem, and on which Evoqua’s and Xylem’s financial advisors’ opinions were based, may significantly alter the value of Evoqua or Xylem or the prices of the Evoqua Common Stock or of the shares of Xylem Common Stock by the time the Merger is consummated. The opinions do not speak as of the time the Merger will be consummated or as of any date other than the dates referenced in such opinions. Because Evoqua and Xylem do not currently anticipate asking their respective financial advisors to update their opinions, the opinions will not address the fairness of the Exchange Ratio, from a financial point of view, at the time of the Evoqua Special Meeting or Xylem Special Meeting, respectively, or at the time the Merger is consummated. The Xylem Board’s recommendation that Xylem shareholders vote “FOR” approval of the Share Issuance Proposal and the Evoqua Board’s recommendation that Evoqua stockholders vote “FOR” the Merger Proposal, however, are each made as of the date of this joint proxy statement/prospectus. For a description of the opinions that Evoqua and Xylem received from their respective financial advisors, please see the sections titled “The Merger—Opinions of Evoqua’s Financial Advisors” and “The Merger—Opinions of Xylem’s Financial Advisors” beginning on pages 105 and 83 of this joint proxy statement/prospectus, respectively.

As a result of the Merger, the combined company may experience a strain in relationships with customers or suppliers that may harm the combined company’s business and results of operations. Certain customers or suppliers may seek to terminate or modify contractual obligations following the Merger whether or not contractual rights are triggered as a result of the Merger. There can be no guarantee that customers and suppliers will remain with or continue to have a relationship with the combined company or do so on the same or similar contractual terms following the Merger. In addition, Xylem has limited experience operating a business similar to Evoqua’s ISS Segment and the market for the types of services offered by Evoqua’s ISS Segment is fragmented. The combined company could lose existing customers or fail to acquire new customers, may not

adequately address this market in terms of the products and services it offers, and may fail to compete successfully with firms offering similar products or services. If any of the customers or suppliers seek to terminate or modify contractual obligations or discontinue the relationship with the combined company, then the combined company’s business and results of operations may be harmed.

Until the consummation of the Merger, Xylem and Evoqua will continue to operate as independent publicly traded companies. The success of the Merger will depend, in part, on Xylem’s ability to successfully integrate Evoqua’s operations. This integration will be complex and time consuming. The failure to successfully integrate and manage the challenges presented by the integration process may result in the combined company not fully achieving the anticipated benefits of the Merger. Potential difficulties that Xylem may encounter as part of the integration process, many of which may be beyond the control of management, include the following:

Among the factors considered by the Xylem Board in connection with its approval of the Merger Agreement were the synergistic and other benefits that could result from the Merger. Xylem cannot provide assurance that such benefits will be realized within the time periods contemplated or at all.

Xylem and Evoqua have incurred and will incur a significant amount of costs and expenses in connection with and as a result of consummating the Merger. A portion of the transaction costs related to the Merger will be incurred regardless of whether the Merger is consummated. Xylem may also incur unanticipated accounting and other costs in the integration of the businesses of Evoqua, including costs which may lead to reserves in the future. While Xylem and Evoqua have assumed that a certain magnitude of transaction expenses will be incurred, factors beyond Xylem’s and Evoqua’s control could affect the total amount or the timing of these expenses. These expenses may exceed the costs historically borne by Xylem and Evoqua as separate companies. These costs could adversely affect the financial condition and results of operations of Xylem and Evoqua or the combined company.

The pro forma financial information contained in this joint proxy statement/prospectus is presented for informational purposes only and may not be an indication of what the combined company’s financial position or results of operations would

have been had the Merger been consummated on the date indicated. The pro forma financial information has been derived from the audited and unaudited historical financial statements of Xylem and Evoqua and certain adjustments and assumptions after giving effect to the Merger. The assets and liabilities of Xylem have been measured at historical values.

In addition, the assumptions used in preparing the pro forma financial information may not prove to be accurate, and other factors may affect the combined company’s financial condition or results of operations following the consummation of the Merger. Any material variance from the pro forma financial information may cause significant variations in the market value of the Xylem Common Stock. See the section titled “Unaudited Pro Forma Condensed Combined Financial Information” beginning on page 32 of this joint proxy statement/prospectus.

This joint proxy statement/prospectus includes certain financial forecasts considered by Xylem and Evoqua in connection with their respective businesses. None of the financial forecasts prepared by Xylem or Evoqua were prepared with a view towards public disclosure or compliance with the published guidelines of the SEC, the United States generally accepted accounting principles (“GAAP”) or the guidelines established by the American Institute of Certified Public Accountants for preparation and presentation of financial forecasts. These forecasts are inherently based on various estimates and assumptions that are subject to the judgment of those preparing them. These forecasts are also subject to significant economic, geopolitical, competitive, industry and other uncertainties and contingencies, all of which are difficult or impossible to predict and many of which are beyond the control of Xylem and Evoqua. Important factors that may affect the actual results of Xylem and Evoqua and cause the internal financial forecasts to not be achieved include risks and uncertainties relating to Xylem’s and Evoqua’s businesses, industry performance, the regulatory environment, general business, economic and geopolitical conditions and other factors described under the section titled “Cautionary Statement Regarding Forward-Looking Statements” beginning on page 47 of this joint proxy statement/prospectus.

In addition, the financial forecasts also reflect assumptions that are subject to change and do not reflect revised prospects for Xylem’s and Evoqua’s businesses, changes in general business or economic conditions or any other transaction or event that has occurred (including the Merger) or that may occur and that was not anticipated at the time the financial forecasts were prepared. In addition, since such financial forecasts cover multiple years, the information by its nature becomes less predictive with each successive year. There can be no assurance that Xylem’s, Evoqua’s or the combined company’s financial condition or results of operations will be consistent with those set forth in such forecasts.

The market value and trading volume of the Xylem Common Stock may be volatile following consummation of the Merger. The stock markets in general have experienced profound volatility that has often been unrelated to the operating performance of particular companies. These broad market fluctuations may adversely affect the market value or liquidity of the Xylem Common Stock, regardless of Xylem’s actual operating performance. As a result, you may suffer a loss on your investment.

The market for Xylem Common Stock will depend on a number of conditions, most of which the combined company cannot control, including:

These and other factors may impair the market for the Xylem Common Stock and the ability of the combined company’s shareholders to sell their shares of Xylem Common Stock at an attractive price. These factors also could cause the market value and demand for the Xylem Common Stock to fluctuate substantially, which may negatively affect the price and liquidity of the Xylem Common Stock. Many of these factors and conditions are beyond the control of the combined company or the shareholders of the combined company.

The results of operations of the combined company, as well as the market value of the common stock of the combined company, after the Merger may be affected by other factors in addition to those currently affecting Evoqua’s or Xylem’s results of operations and the market values of Evoqua Common Stock and Xylem Common Stock. These factors include:

Accordingly, the historical market values and financial results of Evoqua and Xylem may not be indicative for the combined company after the Merger. In addition, general fluctuations in stock markets could have a material adverse effect on the market for, or liquidity of, Xylem Common Stock, regardless of Xylem’s actual operating performance. For a discussion of the businesses of Evoqua and Xylem and certain risks to consider in connection with investing in those businesses, see the documents incorporated by reference by Evoqua and Xylem in the section titled “Where You Can Find More Information” beginning on page 207 of this joint proxy statement/prospectus.

The Xylem Common Stock that Xylem will issue to Evoqua stockholders if the Merger is consummated generally may be sold immediately in the public market. It is possible that some Evoqua stockholders will decide to sell some or all of the shares of Xylem Common Stock that they receive in the Merger. Other Xylem shareholders may also seek to sell shares of Xylem Common Stock held by them following, or in anticipation of, the consummation of the Merger. Any disposition by a significant Xylem shareholder, or the perception in the market that such dispositions could occur, may cause the price of Xylem Common Stock to fall. Any such decline could impair the combined company’s ability to raise capital through future sales of Xylem Common Stock. Further, Xylem Common Stock may not qualify for investment indices and any such failure may discourage new investors from investing in Xylem Common Stock.

Based on the number of shares of Xylem Common Stock outstanding as of January 20, 2023, legacy Evoqua stockholders are expected to own Xylem Common Stock representing approximately 25% of the combined company and legacy Xylem shareholders are expected to own Xylem Common Stock representing approximately 75% of the combined company. Following the consummation of the Merger, the shares of Xylem Common Stock that each legacy Evoqua stockholder will receive as Merger Consideration will represent a percentage ownership of the combined company that is smaller than such stockholder’s percentage ownership of Evoqua before the consummation of the Merger. Further, following the consummation of the Merger, Xylem Common Stock that each legacy Xylem shareholder will continue to hold will represent a percentage ownership of the combined company that is smaller than such shareholder’s percentage ownership of Xylem before the consummation of the Merger. As a result of this reduced ownership percentage, legacy Evoqua stockholders and legacy Xylem shareholders will have less influence over the management and policies of the combined company than they currently have over the management and policies of Evoqua and Xylem as separate companies, respectively.

Following consummation of the Merger, the percentage ownership of combined company shareholders may be diluted because of equity issuances for acquisitions, capital market transactions or otherwise in the future, including, without limitation, equity awards that the combined company may grant to its directors, officers and employees, including employees acquired from Evoqua. Such issuances may have a dilutive effect on the combined company’s earnings per share, which could adversely affect the market value of Xylem Common Stock.

Certain employees of Evoqua will have rights to purchase or receive shares of Xylem Common Stock after the Merger as a result of the conversion of their Evoqua equity awards into Xylem equity awards. The conversion of these Evoqua equity awards into Xylem equity awards is described in further detail in the section titled “The Merger Agreement—Treatment of Options and Other Equity-Based Awards” beginning on page 140 of this joint proxy statement/prospectus. The issuance of shares of Xylem Common Stock pursuant to these awards will dilute the percentage ownership of combined company shareholders. It is also expected that, from time to time after the consummation of the Merger, the Leadership Development & Compensation Committee of the Xylem Board will grant additional equity awards to employees and directors of the combined company under the combined company’s compensation and employee benefit plans. These additional equity awards will have a dilutive effect on the combined company’s earnings per share, which could adversely affect the market value of Xylem Common Stock.

In addition, the combined company’s articles of incorporation will authorize the combined company to issue, without the approval of shareholders, one or more classes or series of preferred stock having such designations, powers, preferences and relative, participating, optional and other special rights, including preferences over Xylem Common Stock with respect to dividends and distributions, as the Xylem Board generally may determine. The terms of one or more classes or series of preferred stock could dilute the voting power or reduce the value of Xylem Common Stock. For example, the repurchase or redemption rights or liquidation preferences that could be assigned to holders of preferred stock could affect the residual value of Xylem Common Stock. For more information, see the section titled “Description of Xylem Capital Stock” beginning on page 176 of this joint proxy statement/prospectus.

The combined company will account for the Merger as an acquisition of a business in accordance with GAAP. Under the acquisition method of accounting, the assets acquired and liabilities assumed of Evoqua and its subsidiaries will be recognized, at their respective fair values and consolidated with Xylem’s net assets. The combined company’s reported financial condition

and results of operations for periods after consummation of the Merger will reflect Evoqua’s balances and results after consummation of the Merger but will not be restated retroactively to reflect the historical financial position or results of operations of Evoqua and its subsidiaries for periods prior to the Merger.

Under the acquisition method of accounting, the total purchase price is allocated to Evoqua’s identifiable tangible and intangible assets acquired and liabilities assumed based on their respective fair market values as of the date of consummation of the Merger, with any excess purchase price allocated to goodwill. To the extent the value of goodwill or intangibles, if any, becomes impaired in the future, the combined company may be required to incur material non-cash charges relating to such impairment. The combined company’s operating results may be significantly impacted from both the impairment and the underlying trends in the business that triggered the impairment.

The shareholders of the combined company may not receive dividends at all or at the same rate they received dividends as Xylem shareholders following the Merger for various reasons, including the following:

Shareholders of the combined company will have no contractual or other legal right to dividends that have not been declared by the Xylem Board.

The combined company may be exposed to increased litigation from shareholders, customers, suppliers, distributors, consumers and other third parties due to the combination of Xylem’s and Evoqua’s businesses following the consummation of the Merger. Such litigation may have an adverse impact on the combined company’s business and results of operations or may cause disruptions to the combined company’s operations.

You should read and consider risk factors specific to Xylem’s business that will also affect the combined company after the Merger. These risks are described in the sections titled “Risk Factors” in Xylem’s Annual Report on Form 10-K for the fiscal year ended December 31, 2022, and in other documents incorporated by reference into this joint proxy statement/prospectus. Please see the section titled “Where You Can Find More Information” beginning on page 207 of this joint proxy statement/prospectus for the location of information incorporated by reference into this joint proxy statement/prospectus.

You should read and consider risk factors specific to Evoqua’s business that will also affect the combined company after the Merger. These risks are described in the sections titled “Risk Factors” in Evoqua’s Annual Report on Form 10-K for the fiscal year ended September 30, 2022, and in other documents incorporated by reference into this joint proxy statement/prospectus. Please see the section titled “Where You Can Find More Information” beginning on page 207 of this joint proxy statement/prospectus for the location of information incorporated by reference into this joint proxy statement/prospectus.

On January 22, 2023, Xylem and Merger Sub entered into the Merger Agreement with Evoqua. The Merger Agreement provides for, among other things, the Merger. Please see the sections titled “The Merger” and “The Merger Agreement” beginning on pages 66 and 139 of this joint proxy statement/prospectus for a description of the Merger, the Merger Agreement and the transactions contemplated thereby.

The unaudited pro forma condensed combined financial information presented in this section titled “Unaudited Pro Forma Condensed Combined Financial Information” has been prepared pursuant to Article 11 of Regulation S-X. Xylem and Evoqua have different fiscal years. Xylem’s fiscal year ends on December 31, whereas Evoqua’s fiscal year ends on September 30. The unaudited pro forma condensed combined balance sheet and the unaudited pro forma condensed combined income statement have been prepared utilizing period ends that differ by one fiscal quarter or less, as permitted by Rule 11-02 of Regulation S-X of the Exchange Act.

The unaudited pro forma condensed combined balance sheet as of December 31, 2022 gives effect to the Merger as if this transaction had been consummated on December 31, 2022 and combines the audited consolidated balance sheet of Xylem as of December 31, 2022 with Evoqua’s audited consolidated balance sheet as of September 30, 2022.

The unaudited pro forma condensed combined income statement for the fiscal year ended December 31, 2022 gives effect to the Merger as if it had been consummated on January 1, 2022, the first day of Xylem’s fiscal year, and combines the historical results of Xylem and Evoqua. The unaudited pro forma condensed combined income statement for the fiscal year ended December 31, 2022 combines the audited consolidated income statement of Xylem for the fiscal year ended December 31, 2022 and Evoqua’s audited consolidated statement of operations for the fiscal year ended September 30, 2022.

The historical financial statements of Xylem and Evoqua have been adjusted in the accompanying unaudited pro forma condensed combined financial information to give effect to pro forma events that constitute transaction accounting adjustments, which are necessary to account for the Merger in accordance with GAAP. The unaudited pro forma adjustments are based upon available information and certain assumptions that Xylem management believes are reasonable.

The unaudited pro forma condensed combined financial information should be read in conjunction with:

Pursuant to the Merger Agreement, Merger Sub will be merged with and into Evoqua, with Evoqua surviving the Merger as a direct, wholly-owned subsidiary of Xylem. Each share of Evoqua Common Stock issued and outstanding immediately prior to the Effective Time, other than the Excluded Shares, will be converted into the right to receive 0.48 shares of Xylem Common Stock. Upon the Closing, legacy Evoqua stockholders are expected to own shares of Xylem Common Stock representing approximately 25% of the combined company and legacy Xylem shareholders are expected to own shares of Xylem Common Stock representing approximately 75% of the combined company. Following the Closing, shares of Xylem Common Stock will continue to be listed on the NYSE. If the Merger Agreement is terminated under certain specified circumstances, Xylem or Evoqua may be required to reimburse certain expenses of the other party, or (i) in the case of Xylem, pay to Evoqua the Xylem Termination Fee under certain specified circumstances or the Regulatory Failure Fee under other specified circumstances and (ii) in the case of Evoqua, pay to Xylem the Evoqua Termination Fee.

Further, under the terms of the Merger Agreement, as of the Effective Time (i) each Evoqua Option, whether vested or unvested, that is then outstanding will be converted into a Xylem Option with the same terms and conditions as were applicable to such Evoqua Option immediately prior to the Effective Time, including with respect to vesting and termination-related provisions (subject to certain adjustments as provided in the Merger Agreement), (ii) each Evoqua RSU that is then outstanding will be converted into a Xylem restricted stock unit with the same terms and conditions as were applicable to such Evoqua

RSU immediately prior to the Effective Time, including with respect to vesting and termination-related provisions, except that such Xylem restricted stock unit will be comprised of that number of Xylem restricted stock units as is equal to the product of the number of shares of Evoqua Common Stock subject to each Evoqua RSU immediately prior to the Effective Time and the Exchange Ratio (with any fractional restricted stock units rounded down to the nearest whole share of Xylem Common Stock), (iii) each Evoqua PSU that is then outstanding will be converted into a Xylem restricted stock unit that vests based on the passage of time with the same terms and conditions as were applicable to such Evoqua PSU immediately upon the consummation of the Merger, including with respect to vesting and termination-related provisions, except that such Xylem restricted stock unit will be comprised of that number of Xylem restricted stock units as is equal to the product of the number of shares of Evoqua Common Stock subject to each Evoqua PSU immediately prior to the Effective Time and the Exchange Ratio (with any fractional restricted stock units rounded down to the nearest whole share of Xylem Common Stock); and (iv) each Evoqua SAR that is then outstanding will be converted into a Xylem SAR, with substantially the same terms and conditions as were applicable to such Evoqua SAR immediately prior to the Effective Time, including with respect to vesting and termination-related provisions, except that such Xylem SAR will be comprised of that number of Xylem SARs as is equal to the product of the number of shares of Evoqua Common Stock relating to each such Evoqua SAR immediately prior to the Effective Time and the Exchange Ratio (rounded down to the nearest whole share of Xylem Common Stock) (clauses (i), (ii), (iii) and (iv) collectively, the “Converted Awards”).

The Merger will be accounted for using the acquisition method of accounting in accordance with ASC 805—Business Combinations, which we refer to as “ASC 805.” Xylem’s management has evaluated the guidance contained in ASC 805 with respect to the identification of the acquirer in the Merger and concluded, based on a consideration of the pertinent facts and circumstances, that Xylem will be the acquirer for financial accounting purposes. Accordingly, Xylem’s cost to acquire Evoqua has been allocated to Evoqua’s acquired assets and liabilities based upon their estimated fair values. The allocation of the purchase price is estimated and is dependent upon estimates of certain valuations that are subject to change. Any differences between the estimated fair value of the consideration transferred and the estimated fair value of the assets acquired and liabilities assumed will be recorded as goodwill. In addition, the final purchase price of Xylem’s acquisition of Evoqua will not be known until the date of the consummation of the Merger and could vary materially from the preliminary purchase price. Accordingly, the allocation of the aggregate Merger Consideration and related adjustments reflected in this unaudited pro forma condensed combined financial information are preliminary and subject to revision based on a final determination of fair value. Refer to Note 1—Basis of Presentation for more information.

The unaudited pro forma condensed combined financial information has been prepared for illustrative purposes only and is not necessarily indicative of what the combined company’s financial position or results of operations actually would have been had the Merger occurred as of the dates indicated. The unaudited pro forma condensed combined financial information also should not be considered indicative of the future results of operations or financial position of Xylem.

The Merger is subject to closing adjustments that have not yet been finalized. Accordingly, the pro forma adjustments are preliminary and have been made solely for the purpose of providing unaudited pro forma condensed combined financial information as required by SEC rules. Differences between these preliminary estimates and the final business combination accounting may be material.

The unaudited pro forma condensed combined financial information has been prepared by Xylem in accordance with Article 11 of Regulation S-X. The unaudited pro forma condensed combined financial information presented is for illustrative purposes only and is not necessarily indicative of what Xylem’s condensed combined income statement or condensed combined balance sheet would have been had the Merger been consummated as of the dates indicated or will be for any future periods. The unaudited pro forma condensed combined financial information does not purport to project the future financial position or results of operations of Xylem following the consummation of the Merger. The pro forma condensed combined financial information reflects transaction accounting adjustments Xylem management believes are necessary to present fairly Xylem’s unaudited pro forma financial position and results of operations following the Closing as of and for the periods indicated. The unaudited pro forma condensed combined financial information does not reflect any cost savings, operating synergies, or revenue enhancements that the combined company may achieve as a result of the Merger, nor does it reflect the costs to integrate the operations of Xylem and Evoqua or the costs necessary to achieve any cost savings, operating synergies, and revenue enhancements.

The unaudited pro forma condensed combined financial information was prepared using the acquisition method of accounting in accordance with ASC 805, with Xylem as the accounting acquirer, using the fair value concepts defined in ASC Topic 820, Fair Value Measurement, and based on the historical consolidated financial statements of Xylem and Evoqua. Under ASC 805, all assets acquired and liabilities assumed in a business combination are recognized and measured at their assumed acquisition date fair value, while transaction costs associated with the business combination are expensed as incurred. The excess of Merger Consideration over the estimated fair value of assets acquired and liabilities assumed, if any, is allocated to goodwill.

The allocation of the aggregate Merger Consideration depends upon certain estimates and assumptions, all of which are preliminary. The allocation of the aggregate Merger Consideration has been made for the purpose of developing the unaudited pro forma condensed combined financial information. The final determination of fair values of assets acquired and liabilities assumed relating to the Merger could differ materially from the preliminary allocation of aggregate Merger Consideration. The final valuation will be based on the actual net tangible and intangible assets of Evoqua existing at the Closing Date.

The transaction accounting adjustments represent Xylem management’s best estimates and are based upon currently available information and certain assumptions that Xylem believes are reasonable under the circumstances. Xylem is not aware of any material transactions between Xylem and Evoqua (prior to the announcement of the Merger) during the periods presented. Accordingly, adjustments to eliminate transactions between Xylem and Evoqua have not been reflected in the unaudited pro forma condensed combined financial information.

Upon consummation of the Merger, Xylem will perform a comprehensive review of Evoqua’s accounting policies. As a result of the review, Xylem may identify differences between the accounting policies of the two companies, which when conformed, could have a material impact on the unaudited pro forma condensed combined financial information. With the information currently available, Xylem has determined that no significant adjustments are necessary to conform Evoqua’s consolidated financial statements to the accounting policies used by Xylem. As a result, the unaudited pro forma condensed combined financial information presented assumes there are no differences in accounting policies. However, as discussed in footnote 2, certain reclassification adjustments have been made to conform Evoqua’s historical financial statement presentation to Xylem’s historical financial statement presentation.

During the preparation of this unaudited pro forma condensed combined financial information, Xylem management performed a preliminary analysis of Evoqua’s financial information to identify differences in financial statement presentation as compared to the presentation of Xylem. With the information currently available, Xylem has made reclassification adjustments to conform Evoqua’s historical financial statement presentation to Xylem’s historical financial statement presentation. Following the Merger, the combined company will finalize the review of its financial statement presentation, which could be materially different from the amounts set forth in the unaudited pro forma condensed combined financial information presented herein.

Refer to the table below for a summary of adjustments made to present Evoqua’s consolidated balance sheet as of December 31, 2022 to conform with that of Xylem’s (amounts in millions):