Water conservation in era where flooding, drought collide

Just 10km from the Bengaluru International Airport, Devanahalli town, situated in a semi-arid zone, has faced persistent water shortage. In recent years, the local municipal corporation was forced to hire private water tankers as 32 of the town’s 130 borewells ran dry. But, for the last six months, the town has been using treated wastewater of Bengaluru blended with rainwater in two lakes to supply 0.2 mld (million litres per day) of water to households.

- Soumya Chatterjee 

Devanahalli’s existing demand, as estimated by the Karnataka water policy, is2.26 mld for its 38,000 residents. Once the second phase of this water treatment project is completed, more than 22% (0.6 mld) of its daily demand can be met by treated water alone, said S Vishwanath, a trustee at Biome Environmental Trust who is working with the town officials and the community to set up an integrated water treatment system using lakes, wells, and a water treatment plant.

But are residents willing to drink treated wastewater? Vishwanath vouches for the quality. “Apart from the water treatment plant, the system is equipped with a 130-micron disc filter, a multimedia filter with activated carbon, ultraviolet disinfection, and an online chlorinator to treat the wastewater before it is integrated into the water supply system. The WTP ensures compliance of treated water with BIS 10500 (drinking water) standards,” he said, adding that “the quality is such that residents may choose to drink it if they wish to”.

Not just in Devanahalli, borewells going dry is a common problem across urban India. With time, traditional means of conserving water using wells, stepwells, ponds, and wetlands have been forgotten. Most of these are lost to real estate or have become garbage dumps. Relentless pumping of water from bore wells, leading to drying up the groundwater reserves, has become the norm. Further, an increase in paved surfaces has meant less water percolates into the ground, affecting natural recharge.