Modak Sagar, one of the seven lakes that supply drinking water to Mumbai and its suburbs, is the third water body to overflow on Tuesday night after Tulsi and Vihar.
This is the first lake, which is located outside Mumbai and supplies 450 million litres to the city, to overflow.
The water stock in the seven lakes is 82% until Tuesday and the current reserve can last around 320 days.
However, there is still no clarity over revoking the 20% daily water cut for each household in Mumbai that was announced by the Brihanmumbai Municipal Corporation (BMC) authorities on August 5 owing to meagre rainfall in the catchment areas.
Earlier, BMC commissioner Iqbal Singh Chahal had told HT that the civic authorities would re-examine the daily water cut rule, if the stock improved.
Upper Vaitarna, Middle Vaitarna, Modak Sagar, Tansa, Bhatsa, Vihar, and Tulsi are the lakes that supply drinking water to Mumbai.
Following heavy monsoon rainfall in Mumbai and neighbouring areas, Modak Sagar, one of the seven reservoirs which supply water to the metropolis, started overflowing on Tuesday night after which the Brihanmumbai Municipal Corporation (BMC) today opened a gate of Modak Sagar dam.
Modak Sagar on the Vaitarna river in Thane district, which has a total storage capacity of 15.8 TMC, overflowed around 9.30 pm, a BMC official said. The BMC has implemented 20 per cent water cut in the city as the dams supplying water to Mumbai had less than 50 percent water stock as of July end.