Companhia de Saneamento Básico do Estado de São Paulo SABESP : BÁSICO DO ESTADO DE SÃO PAULO – SABESP (Form 6-K)

COMPANHIA DE SANEAMENTO BÁSICO DO ESTADO DE SÃO PAULO - SABESP

Publicly-held company

CNPJ No 43.776.517/0001-80

NIRE nº 35.3000.1683-1

MATERIAL FACT

Companhia de Saneamento Básico do Estado de São Paulo - Sabesp ('Company'), in compliance with Rule No. 358 issued by the Brazilian Securities and Exchange Commission ('CVM'), dated as of January 3, 2002, as amended, hereby informs its shareholders and the market in general that, on this date, it was approved, in the 942^th meeting of the Board of Directors of the Company, the 28^th issuance of simple, unsecured and non-convertible debentures, in up to three series, for public distribution, with restricted placement efforts, pursuant to CVM Rule No. 476, dated as of January 16, 2009, as amended ('CVM Rule 476'), in the total amount of up to one billion and two hundred million reais (R$ 1,200,000,000.00) ('Debentures' and 'Offer', respectively), on the respective issuance date, provided that it shall be admitted partial distribution of the Debentures, noted that the issuance is conditioned to the issuance of, at least, one billion reais (R$ 1,000,000,000.00), being, at most, three hundred million reais (300,000,000.00) of the first series.

It shall be adopted the procedure for collecting the investment intentions of the potential professional investors (bookbuilding procedure) in the Debentures, in order to define together with the Company, (i) the number of series of the Offer; (ii) the number of Debentures to be placed in each series of the Offer, according to communicating vessels system; (iii) the final interest to be used in connection to the remuneration of each series; and (iv) the total amount of the Offer, through the cancellation of any Debentures not placed.

The Offer will target professional investors only, in compliance with Articles 11 and 13 of CVM Resolution 30, of May 11, 2021, and Article 2 of CVM Rule 476. According to Article 3 of CVM Rule 476, the Offer will be presented to a maximum of seventy-five (75) professional investors, though the Debentures may only be subscribed by a maximum of fifty (50) professional investors. The process of structuring the Offer and distribution of the Debentures will be undertaken by a consortium of financial institutions belonging to the Securities Distribution System.

The proceeds from the issuance and offering of the Debentures will be used to the refinance of its financial commitments maturing in 2021 and to replenish the Company's cash position.

This Material Fact is disclosed by the Company exclusively for informative purposes, in accordance with current regulations, and should not be interpreted or considered, for all legal purposes, as a material or effort to sell or offer.

In accordance with the applicable regulations and according to the rules of conduct set forth therein, additional information about the Company and the Offer shall be viewed on CVM's website (http://www.gov.br/cvm) and the Company's website (https://ri.sabesp.com.br)).

São Paulo, June 10, 2021.

Rui de Britto Álvares Affonso

Chief Financial Officer and Investor Relations Officer