The current heat wave has increased the rate of evaporation of water from the reservoirs that supply water to Mumbai. With only 37 percent of the water remaining in seven dams, Mumbaikars are worried about water shortages. However, the municipality will not take a decision to reduce water but has requested the state government for reserve water. Accordingly, the municipality has requested 68 thousand million liters of water from 'Upper Vaitarna' and 1 lakh 13 thousand million liters from 'Bhatsa' for Mumbai.
There are two months left for the monsoon season. In the meantime, due to the current increasing heat, there is a possibility that the water supply in the seven reservoirs will further decrease. Earlier, in June 2024, the water supply had decreased by 5 percent. At that time, the reserve storage in the reservoirs was used. Although the municipality has requested this storage this year too, it will be used only when needed, the Water Engineering Department informed.
No system for measurement
The rainfall schedule has changed in the past few years due to climate change. Moreover, the rate of evaporation in reservoirs has increased due to the hot summer. However, the municipality currently does not have any system to measure how much this evaporation is happening and what its volume is.
Stock in seven reservoirs as on 26th March (million litres)
| Reservoir | capacity | Water storage 2023 | 2024 | 2025 |
| Upper Vaitarna | 2,27,047 | 1,24,732 | 1,04,232 | 1,06,713 |
| Modak Sagar | 1,28,925 | 43,355 | 33,002 | 30,613 |
| Tansa | 1,45,080 | 72,189 | 65,608 | 43,955 |
| Middle Vaitarna | 1,93,530 | 30,819 | 20,215 | 80,474 |
| Bhatsa | 7,17,037 | 2,69,013 | 2,23,121 | 2,66,234 |
| Vihar | 27,698 | 13,260 | 12,173 | 13,396 |
| Tulsi | 8,046 | 4,111 | 3,810 | 3,798 |
| Total | 14,47,363 | 5,57,479 | 4,62,160 | 5,45,183 |