According to information from the state owned water utility, Companhia de Agua e Esgoto do estado de Sao Paulo (SABESP), the four-lake Cantareira water system is the largest of six reservoir systems that provide water to some 10 million of the 20 million people living in MRSP.
The six-reservoir system is linked by 48 km of tunnels and canals that provide flow for hydroelectric power and drinking water to MRSP and combined, the system is at or below 3% of its of its 264 billion gallon capacity.
SABESP is the largest water and sanitation company in South America. In the Alto-Tiete basin, the company provides urban water supply and sanitation services to São Paulo City and most municipalities of the basin, operating 195 water treatment plants and 350 wastewater treatment plants.
Because of the extreme water shortage brought on by the drought, SABESP has been forced to pump dead water -- water from reserves below the intake pipes of several reservoirs -- to use as drinking water.