As levels in the lakes that supply water to Mumbai plunged to 5% this summer for the first time since 2019, the city’s municipal corporation has dusted off plans to build a dam on the Gargai river in Wada taluka of Palghar district, north of the city. The project had been shelved because it will submerge around 840 hectares of forest land.
The Brihanmumbai Municipal Corporation is also expediting plans to build a desalination plant, a dam in Palghar’s Jawhar taluka and to link the Damanganga and Pinjal rivers by constructing two dams and tunnels to bring water from Gujarat.
These capital-intensive projects costing more than Rs 22,477 crore aim to deliver an additional 3,200 million litres per day. Mumbai currently receives 3,850 million litres of water a day but by 2041 is estimated to need 5,940 MLD.
However, these projections are overestimated and must be scrutinised for their validity. The challenge that really needs to be addressed is to efficiently manage the water already within the city’s distribution network.
The estimates for how much water Mumbai will need assumes that by 2041, at least 95% of the city’s population will live in planned settlements (non-slums) and will use 240 litres per capita per day for domestic consumption alone. The remaining 5% of the population residing in slums will need to be supplied 150 lpcd.
But this is an overestimate.
To begin with, the per capita domestic demand of 240 lpcd for planned settlements is much higher than the Ministry of Housing and Urban Affairs’s prescription of 150 lpcd for metro cities. Second, the demand of 150 lpcd for slum residents is high, considering the lack of storage spaces in informal settlements and individual flushed toilets.
Further, considering that around half of Mumbai’s population now lives in slums, assuming that the population of people in informal settlements will be 5% by 2041 is unrealistic. Besides, the projections for 2041 put the non-domestic water demand by industrial, commercial and institutional users at 540 MLD.
However, the data shows that after the 1980s, the non-domestic water demand in Mumbai decreased significantly and has stagnated around 300 MLD-350 MLD due to water-consuming industries moving out of the city.
The primary challenge with the water supply in Mumbai is managing water in the distribution network. There is no shortage of water at the city level. The data shows that in the last six decades, the city-level water availability has always been more than 250 lpcd. As per the regional plan of the Mumbai Metropolitan Region released in 2021, the city is supplied with 252 lpcd, excluding water for industrial use. This water is sufficient to meet the current water demand. However, the challenge is to distribute this water equitably across the city.
The city’s old and leaky distribution network has several persistent problems: low pressure that limits the amount of water delivered at the tap, insufficient hours of water supply, sometimes at odd hours and apparent theft. The city loses 34% of its water supply every year – equal to four months of supply
To effectively manage the city’s water, Mumbai’s distribution network should be divided into several supply zones and the water supplied to each area should be monitored using bulk water meters.
During routine operations, these supply zones are expected to be isolated so that the water can be tracked to identify losses, shortages and overconsumption. However, in Mumbai, these supply zones are not isolated and there are several cross-connections across supply zones.
In addition, the network is not fitted with bulk water meters. Nor are all consumer connections metered. As a result, measuring water flows within the city and quantifying water losses is not feasible.
For municipal engineers, it is not easy to trace how much water is flowing to which parts of the city. The estimated (or guesstimated) water losses within the distribution network are around 40%. In such a situation, merely building more dams and losing around 40% of stored water in the city’s distribution network is not a rational technological choice.
Despite water being available in dams, a considerable population within Mumbai relies on groundwater supplied through private tankers due to a poor distribution network. This vulnerability of citizens was revealed in February 2023 when the Mumbai Water Tanker Association called for a strike. Many commercial establishments, institutions, and residents, including those residing in planned buildings, suffered.
The priority should be for the Brihanmumbai Municipal Corporation to assess the water supply challenges using more realistic numbers to quantify the requirements of citizens of varied socio-economic statuses by conducting extensive consumer surveys.
It has never done this.
Before pushing capital-intensive projects to augment supply, the municipality should inform citizens about the status of the water distribution network: the percentage of households connected to piped water supply in different parts of the city, the water pressure, per capita delivery of water in different zones, timings and the reliability of supply.
By reducing water losses, Mumbai can save water and potentially avoid (or postpone) constructing expensive dams and desalination plants.
It must pay greater attention to improving the distribution network. The poorly managed distribution network is the reason citizens suffer. Multi-crore projects that will hurt the environment and Adivasis in the hinterland need to be considered after a more realistic assessment of the problem.
Sachin Tiwale is Fellow, Water and Society Programme, Centre for Environment and Development, Ashoka Trust for Research in Ecology and the Environment, Bangalore. His email ID is sachin.tiwale@gmail.com.
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