Harvesting rainwater? You can't let it down the drain

If the BWSSB has its way, the mere harvesting of rainwater would not be enough. You would have to store it as well.

The Bangalore Water Supply and Sewerage Board (BWSSB) is working on a policy that will make it mandatory for all establishments measuring 2,400 square feet and above to store rainwater as well as treated water so as to reduce the dependency on freshwater.

At present, independent houses, apartments and commercial establishments measuring 2,400 square feet or above have to only harvest rainwater. Apartments with more than 50 units must also set up sewage treatment plants (STPs) to recycle used water.

The BWSSB doesn’t really ask them about its end-use. While most of the harvested rainwater is used to recharge groundwater, the treated water is discharged into sewer lines.

According to the BWSSB, this practice is doing nothing to bring down the demand for freshwater, a scarce resource in today’s times. As many as 1.17 lakh establishments have adapted rainwater harvesting just to avoid being penalised.

The BWSSB says reducing the dependency on freshwater can largely address Bengaluru’s water problem. One of the ways to do this is to use the freshwater only for drinking purposes. Rainwater and treated water can be used for everything else.

“Rainwater can be used for all purposes other than drinking. It’s almost equal to potable water but not recommended for drinking,” B C Gangadhar, Chief Engineer, Maintenance, BWSSB, told DH. “If rainwater is stored and used, the dependency on the Cauvery water will come down.”

The BWSSB is considering bringing a policy that will mandate all establishments above 2,400 square feet to store rainwater as well as treated water.

Gangadhar explained: “We made the STP and the RWH mandatory so that people can use rainwater and treated water for non-potable purposes. But not many people are not doing it. If stored in a separate tank, rainwater or treated water can be used to flush toilets, water the plants, clean vehicles and floors, etc.”

Any failure to store rainwater or treated water will result in a penalty: The BWSSB will either reduce the water supply or impose a 50% fine on the water bill.

Residents are already worried about the repercussions of the BWSSB’s intended move. They say it would be “very hard” to build separate underground sumps for rainwater.