# EDGAR Filing Document

**Accession Number:** 0001170858
**File Stem:** 0001292814-26-001376
**Filing Date:** 2026-3
**Character Count:** 9237
**Document Hash:** 4238dfcb48947f2754671673842d2e34
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001292814-26-001376.hdr.sgml**: 20260319

**ACCESSION NUMBER**: 0001292814-26-001376

**CONFORMED SUBMISSION TYPE**: 3

**PUBLIC DOCUMENT COUNT**: 2

**CONFORMED PERIOD OF REPORT**: 20260318

**FILED AS OF DATE**: 20260319

**DATE AS OF CHANGE**: 20260319

**REPORTING-OWNER**: 

**OWNER DATA:**
- **COMPANY CONFORMED NAME:** Costa Strauch Rafael
- **CENTRAL INDEX KEY:** 0002119934

**ORGANIZATION NAME:**

**FILING VALUES:**
- **FORM TYPE:** 3
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 001-31317
- **FILM NUMBER:** 26772301

**MAIL ADDRESS:**
- **ADDRESS IS A NON US LOCATION:** YES
- **STREET 1:** 300 COSTA CARVALHO STREET
- **CITY:** SAO PAULO
- **PROVINCE COUNTRY:** D5
- **ZIP:** 05429-900
**ISSUER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** COMPANHIA DE SANEAMENTO BASICO DO ESTADO DE SAO PAULO-SABESP
- **CENTRAL INDEX KEY:** 0001170858
- **STANDARD INDUSTRIAL CLASSIFICATION:** WATER SUPPLY [4941]
- **ORGANIZATION NAME:** 01 Energy & Transportation
- **EIN:** 000000000
- **STATE OF INCORPORATION:** D5
- **FISCAL YEAR END:** 1231

**BUSINESS ADDRESS:**
- **ADDRESS IS A NON US LOCATION:** YES
- **STREET 1:** RUA COSTA CARVALHO, 300
- **STREET 2:** SAO PAULO
- **CITY:** SP
- **PROVINCE COUNTRY:** D5
- **BUSINESS PHONE:** 55-11-3388-8110

**MAIL ADDRESS:**
- **ADDRESS IS A NON US LOCATION:** YES
- **STREET 1:** RUA COSTA CARVALHO, 300
- **STREET 2:** SAO PAULO
- **CITY:** SP
- **PROVINCE COUNTRY:** D5

## Ex-24

**Exhibit 24**

**POWER OF ATTORNEY**

KNOW ALL MEN BY THESE PRESENTS, that the undersigned does hereby constitute and appoint **Beatriz Caroline de Sousa Daher**, bearer of Brazilian identity card RG No. 53.212.481-9, enrolled with the Brazilian Individual Taxpayer Registry (CPF) under No 482.274.768-99 and **Ludimila Businaro Aielo**, bearer of Brazilian identity card RG No. 46.164.791-6, enrolled with the Brazilian Individual Taxpayer Registry (CPF) under No 368.220.718-06 as the undersigned's true and lawful attorneys-in-fact to, as applicable:

&nbsp;&nbsp;&nbsp;&nbsp;(1) execute for and on behalf of the undersigned, in
the undersigned's capacity as an officer or director of Companhia de Saneamento Básico do Estado de São Paulo-SABESP
(the "Company"), Forms 3, 4 and 5 in accordance with Section 16(a) of the U.S. Securities Exchange Act of 1934 (the "Exchange
Act") and the rules thereunder and any amendments to the foregoing;

&nbsp;&nbsp;&nbsp;&nbsp;(2) do and perform any and all acts for and on behalf
of the undersigned which may be necessary or desirable to complete and execute any such Forms 3, 4 or 5, complete and execute any amendment
or amendments thereto, and timely file such form with the U.S. Securities and Exchange Commission (the "SEC") and any stock
exchange or similar authority;

&nbsp;&nbsp;&nbsp;&nbsp;(3) to the extent necessary or appropriate, execute for
and on behalf of the undersigned, in the undersigned's capacity as an officer or director of the Company, and submit to the SEC
a Form ID, including amendments thereto, and any other documents necessary or appropriate to obtain codes and passwords enabling the undersigned
to make electronic filings with the SEC of reports required by Section 16(a) of the Exchange Act and the rules thereunder and any amendments
to the foregoing; and

&nbsp;&nbsp;&nbsp;&nbsp;(4) take any other action of any type whatsoever in connection
with the foregoing which, in the opinion of such attorney-in-fact, may be of benefit to, in the best interest of, or legally required
by, the undersigned, it being understood that the documents executed by such attorney-in-fact on behalf of the undersigned pursuant to
this Power of Attorney shall be in such form and shall contain such terms and conditions as such attorney-in-fact may approve to such
attorney-in-fact's discretion.

The undersigned hereby grants to each such attorney-in-fact full power and authority to do and perform any and every act and thing whatsoever requisite, necessary, or proper to be done in the exercise of any of the rights and powers herein granted, as fully to all intents and purposes as the undersigned might or could do if personally present, with full power of substitution or revocation, hereby ratifying and confirming all that such attorney-in-fact, or such attorney-in-fact's substitute or substitutes, shall lawfully do or cause to be done by virtue of this Power of Attorney and the rights and powers herein granted. The undersigned acknowledges that the foregoing attorneys-in-fact, in serving in such capacity at the request of the undersigned, are not assuming, nor is the Company assuming, any of the undersigned's responsibilities to comply with Section 16 of the Exchange Act.

This Power of Attorney shall remain in full force and effect until the undersigned is no longer required to file Forms 3, 4 and 5, as applicable, with respect to the undersigned's holdings of and transactions in securities issued by the Company, unless earlier revoked by the undersigned in a signed writing delivered to the foregoing attorneys-in-fact.

IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to be executed as of the

11th day of March, 2026.

/*s*/ <u>Rafael Costa Strauch</u><br> Name: Rafael Costa Strauch<br>

### UNITED STATES SECURITIES AND EXCHANGE COMMISSION
**Washington, D.C. 20549**

## FORM 3

### INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES

[ ] Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

---

| | | |
|:---|:---|:---|
| **1. Name and Address of Reporting Person**<sup>*</sup><br>Costa Strauch Rafael<br><sub>(Last) (First) (Middle)</sub><br>300 COSTA CARVALHO STREET<br><sub>(Street)</sub><br>SAO PAULO, BRAZIL 05429-900<br><sub>(City) (State) (Zip)</sub> | **3. Issuer Name and Ticker or Trading Symbol**<br>COMPANHIA DE SANEAMENTO BASICO DO ESTADO DE SAO PAULO-SABESP [ SBSP3 ] | **5. If Amendment, Date of Original Filed (Month/Day/Year)**<br>  |
| **2. Date of Event Requiring Statement (Month/Day/Year)**<br>2026-03-18 | **4. Relationship of Reporting Person(s) to Issuer**<br>(Check all applicable)<br>[ ] Director   [ ] 10% Owner<br>[X] Officer (give title below)   [ ] Other (specify below)<br>_New Bus. & Projects Officer_ | **6. Individual or Joint/Group Filing (Check Applicable Line)**<br>[X] Form filed by One Reporting Person<br>[ ] Form filed by More than One Reporting Person |

---

## Table I - Non-Derivative Securities Beneficially Owned

---

|  |  |  |  |
| --- | --- | --- | --- |
| 1. Title of Security | 2. Amount of Securities Beneficially Owned | 3. Ownership Form | 4. Nature of Indirect Beneficial Ownership |

---

## Table II - Derivative Securities Beneficially Owned

---

|  |  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- |
| 1. Title of Derivative Security | 2. Date Exercisable and Expiration Date (Month/Day/Year) | 2. Date Exercisable and Expiration Date (Month/Day/Year) | 3. Title and Amount of Underlying Securities | 3. Title and Amount of Underlying Securities | 4. Conversion or Exercise Price | 5. Ownership Form | 6. Nature of Indirect Beneficial Ownership |
| 1. Title of Derivative Security | Date Exercisable | Expiration Date | Title | Amount or Number of Shares | 4. Conversion or Exercise Price | 5. Ownership Form | 6. Nature of Indirect Beneficial Ownership |
| Restricted Stock Units | <sup>(2)</sup> | <sup>(2)</sup> | Common Shares | 6291 | <sup>(1)</sup> | D |  |
| Restricted Stock Units | <sup>(3)</sup> | <sup>(3)</sup> | Common Shares | 6095 | <sup>(1)</sup> | D |  |

---

### Footnotes:

(1) Each restricted stock unit ("RSU") represents the contingent right to receive one Common Share.

(2) Represents RSUs granted on April 29, 2025, which will vest pro rata on each of May 1, 2026, May 1, 2027, May 1, 2028 and May 1, 2029, subject to continued service as an officer of the issuer.

(3) Represents RSUs granted on December 19, 2025, which will vest pro rata on each of January 1, 2027, January 1, 2028, January 1, 2029 and January 1, 2030, subject to continued service as an officer of the issuer.

**Remarks:**
Due to the issuer's status as a foreign private issuer pursuant to Rule 3a12-3(b) under the Securities Exchange Act of 1934 (the "Act"), the reporting person's transactions in the issuer's equity securities are exempt from Sections 16(b) and 16(c) of the Act. Exhibit 24 - Power of Attorney.

**Signature:** /s/ Beatriz Caroline de Sousa Daher, as attorney-in-fact for Rafael Costa Strauch  
**Date:** 2026-03-18

### Remarks:

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).

** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).

Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.

**Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.**