BWSSB vows water security in Bengaluru by July with rejuvenation of lakes, wells

Bengaluru: The BWSSB has vowed to ensure Bengaluru's water sufficiency by July 1 through lake rejuvenation and building recharge wells. Yet, concerns linger over the scientific rigour of the process.

Scientists and hydrologists believe scientifically backed lake rejuvenation, pits to infiltrate stormwater, and rainwater harvesting would have saved Bengaluru from the crisis even during severe summer. They say unscientific ways of building recharge wells will do more harm than good.

Dr TV Ramachandra, professor at the Centre for Ecological Sciences, Indian Institute of Science (IISc), suggested that recharge wells should be built near stormwater drains to allow rainwater to infiltrate effectively. He also cautions against letting contamination enter the recharge wells, which would pollute the groundwater.

"Building recharge wells at regular intervals closer to stormwater drains is an important step in charging groundwater alongside rejuvenating lakes," he said. 

Ramachandra said proper topography analysis enables identification of suitable points to build recharge wells, adding that low-lying areas are usually ideal because water naturally flows there and soaks into the ground more easily.

About the size of the recharge pits, S Vishwanath from Biome Environmental Solutions said deeper wells enable better infiltration. "Such wells can recharge roughly 500 to 1,000 square meters of catchment area," he added.

"Clean catchment, without any solid waste or sewage, is a must. They should go deep below the clay layer to be able to recharge. A slug test to measure the water flow and hydraulic conductivity in the ground will have added benefits,” Vishwanath said.

He said materials like gravel and sand should not be used in recharge pits. "Ensuring safety with good quality steel grills and concrete slabs (to cover the well) is important. Regular maintenance along with silt traps while collecting rainwater from roads and flyovers are also essential."

Two recharge wells for each new borewell

BWSSB Chairman Ramprasath Manohar V said the board will mandate the construction of two recharge wells for each new borewell to replenish groundwater levels.

A BWSSB engineer told DH that the civic body has already constructed 569 recharge wells across the city in 16 divisions.

Guidelines to build an effective recharge well

1) Clean catchments without solid waste or sewage.

2) Exclusion of materials like grovel or sand.

3) Grease and silt trap on pits along roads and flyovers.

4) Cover the wells with steel grills and concrete slabs to ensure safety.