São Paulo’s Cantareira Water System Put on Alert as Reservoir Levels Fall Below 40 %

In July 2025 the Cantareira system, the main water source for the São Paulo metropolitan area (about 22 million residents), was re‑classified from “attention” to “alert” by the National Water Agency (ANA) and São Paulo State Water Agency (SP Águas). The change follows a drop in stored volume to 39.9 % of usable capacity, crossing the 40 % threshold that triggers an alert.

Under the alert, Sabesp’s water intake from Cantareira is limited to 27 m³/s, down from the normal 31 m³/s. To compensate, the agency may draw water from the transposed reservoir of the Rio Paraíba do Sul, permitted by an agreement among the states of São Paulo, Rio de Janeiro, Minas Gerais and the federal government.

The dry season runs from 1 June to 30 Nov, and authorities may also reduce night‑time water pressure while urging consumers to conserve water. The system already loses around 30 % of treated water through leaks, underscoring the need for infrastructure upgrades and stricter consumer practices.