In the wake of heavy rains over the last few days, the Tansa and Vihar lakes, the key sources of potable water for Mumbai, started overflowing on Wednesday, the Brihanmumbai Municipal Corporation (BMC) said.

Out of the seven reservoirs that supply water to Mumbai, the Vihar, Tansa and Tulsi lakes have overflown so far. The Vihar lake, located in Mumbai`s Sanjay Gandhi National Park, overflowed at 12.48 am, while the Tansa lake, located in neighbouring Thane district, overflowed at 4.35 am on Wednesday, the BMC said.