Mumbai’s water stock dipped by a whopping seven percentage points in the last 15 days as the overall water level in all seven lakes that supply water to the city stood at 30.24 per cent on Tuesday. On March 28, the water stock stood at 37.31 per cent.
Being an island city—surrounded by the sea on three sides—Mumbai draws its water from seven lakes—Tulsi, Vihar, Bhatsa, Tansa, Upper Vaitarna, Middle Vaitarna and Modak Sagar. While two of these lakes are located within Mumbai, the rest are in the satellite districts of Thane, Palghar and Nashik. The catchment area of these lakes gets filled during the monsoon and the water is transported through tunnels to the Brihanmumbai Municipal Corporation’s (BMC) filtration plant. After filtration, water is supplied to every household and commercial establishment through pipelines and reservoirs.
These lakes hold an overall water capacity of 14.4 lakh million litres of water, and considering that the BMC supplies 3,850 million litres per day, the overall stock is supposed to last for 375 days.
Meanwhile, the BMC’s data shows that the overall quantum of water in all the seven lakes stands at 4.37 million litres at present and keeping in mind the daily supply figures, the current stock is expected to last not more than 113 days. Rapid evaporation owing to the extreme temperatures may lead to faster plummeting of the water levels.
“Usually, every one percentage of the overall stock leads to three days of supply. However, in the last two weeks, the stock came down by seven percentage points, which indicates that water stock meant to last for 21 days got over in just 15 days. This is happening because of the heat, which is leading to faster evaporation, and the gap will widen when the temperature increases further by April-end or May,” said an official.
The monsoon usually arrives in Mumbai on June 15. However, over the last few years the city has witnessed delayed monsoon onsets, with rain picking up pace only during the last week of June. And the catchment areas of these lakes are located in the districts of Palghar, Thane, Nashik, where intense rainfall begins not before the middle of July.
In the last week of March, the Maharashtra government allowed the BMC to use a reserve stock of 1.81 lakh million litres, which is expected to last for roughly 48 days, considering the civic body maintains its normal quota of supply. However, if a water cut is imposed, the stock may last for a few more weeks.
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“Considering the current climatic pattern, the monsoon usually arrives in Mumbai by middle June and intense rainfall picks up by July. The catchment areas of these lakes are located in Thane, Nashik and Palghar districts, where good rainfall picks up post July. So keeping these factors in mind, we will need to have a backup stock for at least four months,” the official said.
Civic officials also said that if the quantum of water dips further by the end of April, a water cut may be implemented. “We are monitoring the water stock at present. If the extreme heat condition continues and the water level in the lakes dips below normal levels in the next two weeks, we may have to implement a water cut by the first week of May,” the official added.
© The Indian Express Pvt Ltd