Bengaluru, which is bursting at the seams due to unplanned growth, is hurtling towards a groundwater crisis.

The city will face a shortfall of 217 million cubic metres (2,17,000 mld) of water in 2021, with the shortage expected to balloon exponentially to 518 million cubic metres (5,18,000 mld) by 2041, an expert committee has informed the National Green Tribunal (NGT) in New Delhi.

As of now, the Bangalore Water Supply and Sewerage Board (BWSSB) is supplying 1450 mld/day for the city, whose population has soared to 1.25 crore. According to the WHO, 135 litres of water is needed per day per person to ensure basic needs are met. That figure cannot be met with the current water availability.

The NGT had sought a report from an expert panel comprising members of the Central Pollution Control Board, Ministry of Environment and Forests and Bureau of Indian Standard (BIS) about the status of groundwater in 24 cities, including Bengaluru, where groundwater extraction is very high and .

According to the report, Bengaluru is among 12 cities where the rate of groundwater extraction is more than 100%. With an extraction rate of 141%, the city is in 12th place while Jalandhar in Punjab occupied the top slot with 472%.

Due to fast depletion of groundwater, Bengaluru has to source 94% of its water from surface water by 2021, warned the report.

“The dependency of the cities on surface water is increasing and dependency on groundwater decreasing due to very high extraction of groundwater,” said the report.

The NGT sought the expert panel's report after Niti Aayog raised alarm over the depletion of groundwater in its Composite Water Management Index released in 2018.

The Niti Aayog had earlier said the groundwater supply in the IT city will decrease from 146 billion litres (146 million cubic metres) in 2018 to 36 billion litres (million cubic metres) in 2041 due to over-exploitation.