Mumbai's water woes: Four months' worth of water just disappears!

Visitors at Vihar lake near Goregaon in the month of July. File Pic/Satej Shinde

The Brihanmumbai Municipal Corporation (BMC) claims that non-revenue water (NRW), which refers to water losses, has decreased from 38 per cent to 34 per cent over the past two years. However, this still equates to losing the equivalent of four months' worth of water supply. Ideally, the loss rate should not exceed 15 per cent of the total supply.

NRW encompasses water that is supplied but not paid for, including losses from leakage, unbilled water, illegal connections, faulty water meters, and inaccurate readings. Of the 3,950 million litres of water received daily, 1,500 million litres were lost - a significant amount.

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Tansa lake at Shahapur in Thane. File Pic

"We cannot classify the entire 34 per cent as loss, as some of it may be consumed but unaccounted for in billing and revenue. Pipeline bursts, often caused by infrastructure projects, contribute to these losses. We work to reduce repair times to minimise losses," said Purushottam Malavade, chief of the BMC's hydraulic engineering department, during a visit to the Middle Vaitarna Dam. However, Malavade could not provide a detailed breakdown of losses from leaks, theft, or unmetered bills.

"The NRW has been reduced by 4 per cent through various initiatives, such as replacing aging pipelines with new tunnels and upgrading water pipelines to reduce leaks. The BMC is also using advanced technology to detect leaks in underground pipes," added Malavade. The BMC claims that complaints about water contamination have decreased over the years. According to the BMC, water contamination levels are below 0.3 NTU (Nephelometric Turbidity Unit, which measures suspended particles in water), and residual chlorine levels are at 0.2 ppm

Mumbai has a water supply network spanning over 5,000 km. Water from the city's 27 balance reservoirs is distributed to 3.89 lakh customers through this extensive network, excluding an additional 800 km of water tunnels and large pipelines that bring water from dams to treatment plants and then to the reservoirs.

Kids playing on water pipelines in Bandra. Pic/Atul Kamble

The 5,000 km network comprises pipes with diameters ranging from 150 mm to 2400 mm. Maintaining such a vast system is a significant challenge. "There are 1,100 sanctioned posts, but only 712 engineers are currently employed, with the remaining positions vacant. Managing with such limited manpower to control supply pressure and address leakages is difficult," an official from the BMC said.

Despite the city's lakes being full, water supply issues persist. For the past three months during summer, the city has experienced water cuts, a trend that is likely to continue this year as well, according to the hydraulic department chief, as reported by mid-day on September 25. "The lakes are full, and BMC has a water supply management plan in place until the end of next July with 3,950 MLD of water. However, during festivals or hot periods like October or March, additional water is required.

Moreover, water lines often burst due to infrastructure projects, leading to wastage. As a result, despite the management efforts, the supply may sometimes fall short before July ends," said Malavade. He also mentioned that the BMC seeks permission to use reserved water from the lakes. This year, approximately 60,000 million litres of reserve stock was used, yet the city still faced water cuts from May to mid-July.