COMPANHIA DE SANEAMENTO BASICO DO ESTADO DE SAO PAULO-SABESP

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 20-F

¨ REGISTRATION STATEMENT PURSUANT TO SECTION 12(b) OR (g) OF THE SECURITIES EXCHANGE ACT OF 1934

OR

x ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 FOR THE FISCAL YEAR ENDED DECEMBER 31, 2024

OR

¨ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 FOR THE TRANSITION PERIOD FROM ________________ TO ________________

OR

¨ SHELL COMPANY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

Date of event requiring this shell company report: ________________

Commission file number 001-31317

Companhia de Saneamento Básico do Estado de São Paulo-SABESP

(Exact name of Registrant as specified in its charter)

Basic Sanitation Company of the State of São Paulo-SABESP

(Translation of the Registrant’s name into English)

Federative Republic of Brazil

(Jurisdiction of incorporation or organization)

Rua Costa Carvalho, 300

05429-900 São Paulo, SP, Brazil

(Address of principal executive offices)

**Daniel Szlak **

dri@sabesp.com.br (+55 11 3388 8000)

Rua Costa Carvalho, 300 05429-900 São Paulo, SP, Brazil

Securities registered or to be registered pursuant to Section 12(b) of the Act:

Shares are not listed for trading, but only in connection with the registration of American Depositary Receipts pursuant to the requirements of the New York Stock Exchange.

Securities registered or to be registered pursuant to Section 12(g) of the Act: None

Securities for which there is a reporting obligation pursuant to Section 15(d) of the Act: None

Indicate the number of outstanding shares of each of the issuer’s classes of capital or common stock as of the close of the period covered by the annual report.

683,509,868 Shares of Common Stock

1 Share of Preferred Stock

Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act.

If this report is an annual or transition report, indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 from their obligations under those Sections.

Yeso No x

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports) and (2) has been subject to such filing requirements for the past 90 days.

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files).

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, or an emerging growth company. See the definition of “large accelerated filer,” “accelerated filer,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

If an emerging growth company that prepares its financial statements in accordance with U.S. GAAP, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards† provided pursuant to Section 13(a) of the Exchange Act. o

† The term “new or revised financial accounting standard” refers to any update issued by the Financial Accounting Standards Board to its Accounting Standards Codification after April 5, 2012.

Indicate by check mark whether the registrant has filed a report on and attestation to its management’s assessment of the effectiveness of its internal control over financial reporting under Section 404(b) of the Sarbanes-Oxley Act (15 U.S.C. 7262(b)) by the registered public accounting firm that prepared or issued its audit report. x

If securities are registered pursuant to Section 12(b) of the Act, indicate by check mark whether the financial statements of the registrant included in the filing reflect the correction of an error to previously issued financial statements. o

Indicate by check mark whether any of those error corrections are restatements that required a recovery analysis of incentive-based compensation received by any of the registrant’s executive officers during the relevant recovery period pursuant to §240.10D-1(b). o

Indicate by check mark which basis of accounting the registrant has used to prepare the financial statements included in this filing:

If “Other” has been checked in response to the previous question, indicate by check mark which financial statement item the registrant has elected to follow.

Item 17 o Item 18 o

If this is an annual report, indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act).

Yeso Nox

TABLE OF CONTENTS

PRESENTATION OF FINANCIAL AND OTHER INFORMATION

General

We maintain our books and records inreais. We prepare our consolidated financial statements (“Consolidated Financial Statements”) in accordance with International Financial Reporting Standards (“IFRS”), as issued by the International Accounting Standards Board (“IASB”). Our audited consolidated financial statements as of December 31, 2024 and 2023 and for each of the three years in the period ended December 31, 2024 (“2024 Consolidated Financial Statements”) are included in this annual report on Form 20-F.

The financial statements of subsidiaries are included in the consolidated financial statements from the date we obtain control until the date when such control ceases to exist. All financial information for the years ended December 31, 2024 and 2023 were prepared on a consolidated basis, while all financial information for the year ended December 31, 2022 was prepared on an individual basis because we had no subsidiaries to consolidate in that year.

Certain figures included in this annual report have been subject to rounding adjustments. Accordingly, figures shown as totals in certain tables may not be an arithmetic aggregation of the figures which precede them.

Privatization

On December 8, 2023, the State of São Paulo enacted State Law No. 17,853/2023, providing the authorization for our proposed privatization and its general guidelines. This law authorized the State of São Paulo to reduce or dilute its controlling interest in us through a sale of its common shares through an auction or secondary offering on the relevant stock exchanges within and outside of Brazil or via a primary public offering of our common shares within and outside of Brazil. In addition to authorizing our privatization, the law also brought forward the target for providing drinking water to 99% of the population and sewage collection and treatment for 90% of the population (the “Universalization Target”) for the state of São Paulo from 2033 to 2029.

On July 22, 2024, the State of São Paulo closed a secondary offering of 220,470,000 of our common shares (including common shares represented by ADRs), effectively reducing their interest in us from 50.26% to 18.00% and completing our privatization process (the “Privatization”).

As part of this process, the State of São Paulo conducted a public competitive process pursuant to which it sold 15% of our total share capital through a priority offering to a “reference investor”. The finalist reference investor was Equatorial Energia S.A. (the “Reference Investor”).

On July 18, 2024, the State of São Paulo and the Reference Investor entered into an investment agreement substantially upon the terms set out in the Form 6-K furnished to the SEC on July 1, 2024 (the “Investment Agreement”). The Investment Agreement provides certain specific rights and obligations for the State of São Paulo and the Reference Investor and is valid until January 1, 2035. We highlight the following:

State Law No. 17,853/2023 also provided that, in case of our Privatization is consummated, our bylaws must be amended to provide for a special class of preferred share, owned exclusively by the State of São Paulo (referred to as a “golden share”), which will grant the State of São Paulo veto power over proposed changes to: (i) our name and headquarters; (ii) our corporate purpose of providing water and sewage services; and (iii) any provisions in our bylaws regarding limits on the exercise of voting rights attributed to shareholders or groups of shareholders. Our shareholders approved these changes to our bylaws conditional upon the consummation of our Privatization at an Extraordinary Shareholders’ Meeting held on May 27, 2024. These changes to our bylaws included, among others, an authorized capital provision, the golden share terms and conditions, and, in order to both stimulate the shareholding dispersion and avoid hostile takeover, our bylaws also establishes that, in case one or a group of shareholders acquires 30% or more of our common shares, such shareholder(s), will have to make a tender offer to our other shareholders at a price established in our bylaws that includes a 200% premium (antitakeover provision), subject to certain exceptions. Our antitakeover provision may be dismissed by approval of our shareholders´ meeting. These changes to our bylaws, including the voting limitation described below, became effective on July 22, 2024, the date of our Privatization. For more information, see “Item 3.D. Risk Factors—Risks Relating to Our Privatization—Our Privatization and the changes to our operational structure arising from our Privatization may still be challenged. A court ruling favorably to such challenge could adversely affect our operations and the market price of our common shares and ADSs. The absence of a single controlling shareholder or group of controlling shareholders may impact our ability to efficiently approve certain transactions and could potentially delay critical decision-making processes, which may adversely affect our business and results of operations.”

On May 24, 2024, we and URAE-1 signed the Concession Agreement for URAE-1, which came into force on July 23, 2024 following the consummation of our Privatization, and introduced significant changes to the prior economic-regulatory model. For more information, see “Item 4.B. Business Overview—Tariff Readjustments and Reviews—Economic-regulatory model in the draft Concession Agreement for Public Water Supply and Sanitation Services for the URAE-1 Southeastern region,” and “Item 3.D. Risk Factors—Risks Relating to the Regulatory Environment—We are exposed to risks associated with the Concession Agreement for URAE-1, which may materially impact our financial condition and operating results.”

For the risks associated with our Privatization, see “Item 3.D. Risk Factors—Risks Relating to Our Privatization.”

Other Information

In this annual report, unless the context otherwise requires, references to “we,” “us,” “our,” “Company,” or “SABESP” refer to Companhia de Saneamento Básico do Estado de São Paulo – SABESP.

In addition, references to:

Information in this annual report related to liters, water and sewage volumes, number of employees, kilometers, water and sewage connections, population served, operating productivity, water production, water and sewage lines (in kilometers), water loss index and investment in programs has not been audited.

Market Information

We make statements in this annual report about our market share and other information relating to Brazil and the industry in which we operate. We have made these statements on the basis of information from third-party sources and publicly available information that we believe is reliable, such as information and reports from the Brazilian Institute of Geography and Statistics (Instituto Brasileiro de Geografia e Estatística – “IBGE”), and the State Data Analysis System Foundation (Fundação Sistema Estadual de Análise de Dados – “SEADE”), among others. We have no reason to believe that any of this information is inaccurate in any material respect.

References to urban and total population in this annual report are estimated based on research prepared by SEADE entitled “Projections of Population and Residences for the municipalities of the State of São Paulo: 2010-2050” (Projeção da População e dos Domicílios para os Municípios do Estado de São Paulo: 2010-2050).

Our Contracts and the Municipalities We Serve

Throughout this document, we refer to the 375 municipalities we serve directly and the two municipalities which we account for in our wholesale segment (Mogi das Cruzes and São Caetano do Sul), since our revenue for the year ended December 31, 2024 is derived from these municipalities. The 375 municipalities include 371 municipalities covered by the Concession Agreement for URAE-1, and four governed by individual contracts (municipalities of Miguelópolis, Quintana, Nova Guataporanga and Olímpia).

CAUTIONARY STATEMENTS ABOUT FORWARD-LOOKING STATEMENTS

This annual report includes forward-looking statements, mainly in Items 3 through 5. We have based these forward-looking statements largely on our current expectations and projections about future events and financial trends affecting our business. These forward-looking statements are subject to risks, uncertainties and assumptions, including, among other factors:

The words “believe,” “may,” “estimate,” “continue,” “anticipate,” “plan,” “intend,” “expect” and similar words are intended to identify forward-looking statements. In light of these risks and uncertainties, the forward-looking events and circumstances discussed in this annual report might not occur. Our actual results could differ substantially from those anticipated in our forward-looking statements. Forward-looking statements speak only as of the date they were made, and we do not undertake any obligation to update or revise any forward-looking statements, whether as a result of new information, future events or otherwise, unless required by law. Any such forward-looking statements are not an indication of future performance and involve risks.