COMPANHIA DE SANEAMENTO BÁSICO DO ESTADO DE SÃO PAULO - SABESP

COMPANHIA DE SANEAMENTO BÁSICO DO ESTADO DE SÃO PAULO - SABESP Corporate Taxpayer s ID (CNPJ): 43.776.517/0001-80 Company Registry (NIRE): 35.3000.1683-1 EXCERPT OF THE MINUTES OF THE EIGHT HUNDRED THIRTY-NINTH MEETING OF THE BOARD OF DIRECTORS The undersigned members of the Board of Directors of Companhia de Saneamento Básico do Estado de São Paulo SABESP listed below met at the meeting room in the Company s headquarters, at Rua Costa Carvalho n 300, São Paulo, at 9:00 a.m. on May 12, 2017, at the call of the Chairman of the Board of Directors, Benedito Pinto Ferreira Braga Junior, on an ordinary basis, pursuant to the caput of article 12 of the Bylaws. (...) Proceeding with the works, the Chairman of the Board of Directors moved on to item 3 of the agenda, Approval of the conditions applicable to Sabesp s 21 st issue of debentures, pursuant to article 59 of the Brazilian Corporation Law (final specific conditions) (time: 20 ), giving the floor to the Chief Financial Officer and Investor Relations Officer, Rui de Britto Álvares Affonso, and the Funding and Investor Relations Superintendent, Mário Azevedo de Arruda Sampaio, so that they could present the matter based on Executive Board Resolution no. 0132/2017, of May 10, 2017, Internal Communications no. 022/2017, of May 10, 2017, and a PowerPoint presentation, all of which were filed in the meeting s electronic folder. The matter was discussed and then voted on, pursuant to article 59, paragraph 1 of Law 6,404, of December 15, 1976, as amended ( Brazilian Corporation Law ), and in compliance with items X and XIII of article 13 of the Bylaws, and the Board of Directors unanimously approved the conditions applicable to the 21 st issue of simple unsecured nonconvertible debentures, in up to two (2) series, for public offering, with restricted placement efforts, pursuant to CVM Instruction 476, of January 16, 2009, as amended ( Debentures, Offering, CVM Instruction 476, respectively), as described below: 1. Issuer: Companhia de Saneamento Básico do Estado de São Paulo SABESP. 2. Issue Amount: The total issue amount will be five hundred million reais (R$500,000,000.00) on the Issue Date (as defined below). The amount of each series will be defined based on the Book Building Process and the Debentures will be allocated between the series using the communication vessels system, i.e. the number of Debentures of any series should be deducted from the total number of Debentures, thus limiting the number of Debentures to be allocated to the other series ( Communicating Vessels System ). 3. Number of Series: The issue will be carried out in up to two (2) series. The number of Debentures to be allocated to each series will be defined in accordance with the Book Building process and the Debentures will be allocated between the series using the Communicating Vessels System. The Debentures of the Offering distributed within the scope of the first series will be called First Series Debentures and the Debentures of the Offering distributed within the scope of the second series will be called Second Series Debentures. 4. Type: Unsecured. 1

5. Issue Date: For legal purposes, the Debenture issue date will be June 15, 2017 ( Issue Date ). 6. Type, Form and Convertibility: The Debentures will be registered, book-entry and simple, i.e. not convertible into shares issued by the Company, without the issue of certificates or provisional certificates. 7. Number: Five hundred thousand (500,000) Debentures will be issued in up to two (2) series, and the number of Debentures to be allocated to each series will be defined in accordance with the Book Building Process. 8. Nominal Unit Value: One thousand reais (R$1,000.00) on the Issue Date ( Nominal Unit Value ). 9. Placement and Distribution Procedure: The Debentures will be distributed through a public offering with restricted placement efforts, pursuant to CVM Instruction 476, under a firm placement guarantee, intermediated by financial institutions members of the securities distribution system (jointly, Coordinators ). The Offering Coordinators may approach a maximum of seventy-five (75) professional investors, pursuant to article 9-A of CVM Instruction 539, of November 13, 2013, as amended ( Professional Investors ), and the Debentures may be subscribed to or acquired by a maximum of fifty (50) Professional Investors. Pursuant to article 6 of CVM Instruction 476, the registration of the Offering with the CVM is automatically waived. 10. Book Building Process: The Book Building Process, organized by the Coordinators, without accepting reservations by Professional Investors, with no minimum or maximum lots, will be carried out in order to determine demand for the Debentures at different interest rate levels ( Book Building Process ) and define, together with the Issuer: (i) the issue of each series of the Issue, or the issue of the Debentures in a single series and, if the issue of the Debentures in two (2) series is confirmed, the number of First Series Debentures and Second Series Debentures; and (ii) the remuneration of First Series Debentures, in case of issue of First Series Debentures, and the remuneration of Second Series Debentures, in case of issue of Second Series Debentures. The result of the Book Building Process will be ratified through an amendment to the Indenture, with no need for any additional corporate approval by the Company or approval by the Debenture holders. 11. Subscription Price and Payment: The Debentures will be subscribed to and paid-up in cash, in domestic currency, in the primary market, at their Nominal Unit Value, on the actual subscription date ( Pay-in Date ), through the Asset Distribution Module MDA ( MDA ), managed and operated by CETIP S.A. Mercados Organizados ( CETIP ), as of the initial date of distribution of the Debentures. 12. Monetary Restatement: The Nominal Unit Value of the Debentures will not be restated using any index. 13. Remuneration: The Debentures will be entitled to the following remuneration: (a) Remuneration of First Series Debentures: First Series Debentures will be entitled to remuneration ( First Series Remuneration ) corresponding to one hundred percent (100.0%) of the accumulated variation of the average daily rate of one-day over extragrupo DI interbank deposits ( DI Rate ) expressed as an annual percentage, based on two hundred and [KA1] Comentário: Estamos supondo que procurar = abordar, entrar em contato. Caso procurar = buscar, favor trocar "approach" por "seek". [k2] Comentário: Entendemos corretamente? 2

fifty-two (252) working days, calculated and disclosed by the CETIP in the daily bulletin available on its website (http://www.cetip.com.br), plus the maximum spread or surcharge to be defined in the Book Building Process, limited to zero point seventy-eight hundredths (0.78%) per year, based on two hundred and fifty-two (252) working days. The First Series Remuneration will be calculated on an exponential and cumulative basis, proportionally to the number of working days elapsed since the Pay-in Date or the last date of payment of the First Series Remuneration, as applicable, based on the Nominal Unit Value of First Series Debentures, and paid at the end of each Yield Period. (b) Remuneration of Second Series Debentures: Second Series Debentures will be entitled to remuneration ( Second Series Remuneration and, jointly with the First Series Remuneration, Remuneration ) corresponding to one hundred percent (100.0%) of the accumulated DI rate variation, expressed as an annual percentage, based on two hundred and fifty-two (252) working days, calculated and disclosed by the CETIP in the daily bulletin available on its website (http://www.cetip.com.br), plus the maximum spread or surcharge to be defined in the Book Building Process, limited to zero point nine hundred and twenty-five thousandths (0.925%) per year, based on two hundred and fifty-two (252) working days. The Second Series Remuneration will be calculated on an exponential and cumulative basis, proportionally to the number of working days elapsed since the Pay-in Date or the last date of payment of the Second Series Remuneration, as applicable, based on the Nominal Unit Value of Second Series Debentures, and paid at the end of each Yield Period. (c) For the purposes of calculation of the Remuneration, Yield Period is defined as the time interval between the Pay-in Date, inclusive, in the case of the first Yield Period, or the immediately prior date of payment of Remuneration, and the date of payment of Remuneration, exclusive, corresponding to the period in question. 14. Payment of Remuneration: Except for the events of total early redemption of First Series Debentures and/or early maturity, as defined in the Indenture ( Indenture ), the amounts related to Remuneration should be paid every six months, for all series, always on the 15 th of December and June of each year, with the first payment due on December 15, 2017 and the last payment due on the First Series Maturity Date, in the case of First Series Debentures, and on the Second Series Maturity Date, in the case of Second Series Debentures. 15. Term and Maturity Date: Except for the events of total early redemption of First Series Debentures and/or early maturity, if applicable, as defined in the Indenture, First Series Debentures will mature in three (3) years, as of the Issue Date, i.e. on June 15, 2020 ( First Series Maturity Date ), and Second Series Debentures will mature in five (5) years, as of the Issue Date, i.e. on June 15, 2022 ( Second Series Maturity Date ). 16. Guarantee: None. 17. Amortization of the Nominal Unit Value: Except for the events of total early redemption of First Series Debentures, extraordinary voluntary amortization and/or early maturity, as defined in the Indenture, the amortization of First Series Debentures will be carried out in a single installment, at an amount corresponding to the Nominal Unit Value of First Series Debentures or the balance of the Nominal Unit Value of First Series Debentures, as applicable, on the First Series Maturity Date. The 3

amortization of Second Series Debentures will be carried out in two (2) annual, equal and consecutive installments, with the first installment due on June 15, 2021, at an amount corresponding to fifty percent (50%) of the Nominal Unit Value of Second Series Debentures or the balance of the Nominal Unit Value of Second Series Debentures, as applicable, and the second installment due on the Second Series Maturity Date, at an amount corresponding to the balance of the Nominal Unit Value of Second Series Debentures. 18. Payment Location: The payments the Debentures are entitled to will be made by the Issuer on the respective maturity date using, as applicable: (a) the procedures adopted by the CETIP for Debentures held in electronic custody by the CETIP; and/or (b) the procedures adopted by the liquidator bank for Debentures that are not held in electronic custody by the CETIP ( Payment Location ). 19. Maturity Extension: The maturity of any payment obligations arising from the Debentures will be extended until the first subsequent business day if the due date falls on a weekend or bank holiday in the Payment Location or in the city and state of São Paulo, without any increase in the amounts payable, except for payments to be made through the CETIP, in which case an extension is granted only when the payment date falls on a national holiday, Saturday and/or Sunday. 20. Allocation of the Proceeds: The proceeds from the issue of Debentures will be used to refinance financial commitments due in 2017 and recompose the Issuer s cash. 21. Registration for Placement and Trading: The Debentures are registered for: (a) public distribution in the primary market through the MDA, managed and operated by the CETIP, with the distribution being financially settled through the CETIP; and (b) trading in the secondary market through CETIP21 Securities ( CETIP21 ), managed and operated by the CETIP, with the trades being financially settled and the Debentures held in electronic custody by the CETIP. 22. Voluntary Acquisition: The Issuer may, at any time, acquire outstanding Debentures, pursuant to paragraph 3 of article 55 of the Brazilian Corporation Law. The Debentures acquired by the Issuer may be: (i) cancelled, through a resolution by the Issuer; (ii) held in treasury by the Issuer; or (iii) once again placed in the market, observing the trading restrictions in CVM Instruction 476. The Debentures acquired by the Issuer to be held in treasury, if and when they are placed again on the market, will be entitled to the same Remuneration as the other outstanding Debentures of the respective series. 23. Total Early Redemption: The early redemption of First Series Debentures may occur at any time, at the Issuer's discretion, as of the eighteenth (18 th ) month from the Issue Date, i.e. on December 15, 2018, inclusive, for all outstanding First Series Debentures ("Total Early Redemption of First Series Debentures"). The Total Early Redemption of First Series Debentures will take place through the payment of the Nominal Unit Value of First Series Debentures plus the First Series Remuneration, calculated proportionally, from the Pay-in Date or the last date of payment of the First Series Remuneration, as applicable, to the actual date of redemption, plus a premium to holders of First Series Debentures, equivalent to zero point twenty hundredths (0.20%), to be calculated based on the terms in the Indenture, which will be paid to holders of First Series Debentures, pursuant to the procedure adopted by the CETIP for Debentures held in electronic custody by the CETIP. The early redemption of Second Series Debentures will not be allowed. 4

24. Extraordinary Voluntary Amortization: The extraordinary voluntary amortization of First Series Debentures may occur at any time, at the Issuer's discretion, as of the eighteenth (18 th ) month from the Issue Date, i.e. on December 15, 2018, inclusive ("Extraordinary Voluntary Amortization of First Series Debentures"). The Extraordinary Voluntary Amortization of First Series Debentures shall be preceded by a written notice to the Fiduciary Agent at least ten (10) days prior to the payment of the Extraordinary Voluntary Amortization and is limited to ninety percent (90%) of the Nominal Unit Value of First Series Debentures or the balance of the Nominal Unit Value of First Series Debentures, as applicable, plus the First Series Remuneration calculated proportionally since the Pay-in Date or the last date of payment of the First Series Remuneration, as applicable, and other charges due and not paid until the date of the Extraordinary Voluntary Amortization, plus a premium equivalent to zero point twenty hundredths (0.20%) on the amount corresponding to the Extraordinary Voluntary Amortization of First Series Debentures, to be calculated pursuant to the terms in the Indenture. The extraordinary voluntary amortization of Second Series Debentures will not be allowed. 25. Default Charges: Without prejudice to the Remuneration, if there is any delay in the payment of any amount due to Debenture holders, the late payments will be subject to a non-compensatory fine of two percent (2%) of the amount due and interest on arrears calculated from the date of default to the date of actual payment, at one percent (1%) per month on the overdue amount, regardless of any court or out-of-court notice or notification, in addition to any collection expenses incurred by the Debenture holders. 26. Early Maturity Events: The Debentures will have their early maturity declared in the events set forth in the Indenture, as negotiated with the Coordinators. 27. Renegotiation: The Debentures shall not be renegotiated. The Board of Directors also authorized the members of the Executive Board, pursuant to the legal and statutory provisions, to perform any and all acts related to the 21 st issue of simple unsecured nonconvertible debentures, in up to two (2) series, including, but not limited to, negotiating and executing the Indenture and any amendments thereto, as well as the agreement for the coordination, placement and public distribution under a firm placement guarantee; signing any and all documents and performing all acts necessary for this purpose, being also able to determine whether there will be one or two series and the number of Debentures to be allocated to each Series; and establishing the Debentures remuneration, pursuant to item 10 above, after the completion of the Book Building Process to be conducted by the Coordinators, within the limits and parameters established herein. Finally, the Board of Directors ratified all the acts related to the 21 st issue previously performed by the Executive Board. (...) The minutes, after being approved, will be signed by the attending members of the Board of Directors: Benedito Pinto Ferreira Braga Junior, Francisco Luiz Sibut Gomide, Francisco Vidal Luna, Jerônimo Antunes, Jerson Kelman and Luis Eduardo Alves de Assis. This is a free translation of the excerpt of the minutes that will be drawn up in the book of minutes of Board of Directors meetings. São Paulo, May 12, 2017. 5

Benedito Pinto Ferreira Braga Junior Chairman of the Board of Directors Marialve de S. Martins Secretary of the Board of Directors 6