Sabesp started to operate in 1973, in order to implement the National Sanitation Plan – PLANASA, a Brazilian government program that financed capital investments and helped develop state water and sewage companies, using funds from the FGTS (Workers’ Severance Pay Fund). Since then, other publicly – or state-owned companies related to water supply and sewage collection and treatment in the state have been merged into Sabesp.

In the 1980’s, SABESP invested in sewage collection and treatment throughout the entire state. In 1985, the Greater São Paulo Water Fluoridation Program was completed, benefiting 13 million people. In 1992, Sabesp signed agreements for the depollution of the Tietê River and the recovery of the Guarapiranga Reservoir.

In 2002, Sabesp joined the Novo Mercado trading segment of the Securities, Commodities and Futures Exchange – Brasil, Bolsa, Balcão3. It also registered with the Securities and Exchange Commission – SEC and its shares began to be traded on the NYSE as Level III ADRs (American Depository Receipts). In 2004, the state of São Paulo held a new, simultaneous public offering of registered common shares on both the Brazilian and international markets.

In accordance with State Law 119/73, which authorized the creation of Sabesp, the São Paulo State Finance Department must maintain, either directly or indirectly, at least half of Sabesp’s voting capital.

In 2008, Sabesp resolved to expand geographically and add new types of services related to environmental sanitation and energy, in accordance with Complementary State Law 1025, and together with OHL Médio Ambiente, Inima S.A.U. – Unipersonal, Técnicas y Getion Medioambiental S.A.U. and Estudos Técnicos e Projetos ETEP Ltda., founded Sesamm – Serviços de Saneamento de Mogi Mirim S.A.

In September, 2017, the state law 16525/17 was passed, which authorizes the Government of São Paulo to establish a Controlling Company to hold all shares in Sabesp that belong to São Paulo State Government.