Harvesting a hit, but B’luru lets 90% of rainwater go waste

With Bengaluru draining away as much as 90% of its rainwater, recent success stories demonstrate how the city is squandering a potential panacea for the water crisis looming large following a sub-par southwest monsoon. 

Harvested rainwater has helped fill up the sumps and wells of many households, drastically reducing their dependence on Cauvery water or groundwater. They no longer have to worry about inadequate piped water supply, drying borewells or surging water tanker prices. 

Take the example of Raghuram, who has installed an 8,000-litre rainwater sump in his Vidyaranyapura home. The well in the house is full after the September rains. The family now depends on Cauvery water only for drinking purposes. 

“Even half an hour of rainfall helps fill the tanks. We are a family of eight and manage all our needs with harvested rainwater,” Raghuram said. “Just imagine the benefits if all citizens adopt RWH.” 

Sarjapur resident Abhay M says RWH systems also help improve the groundwater levels. “Once the tanks and sumps are full, the water is directed to the recharge pits. Over the last two years, we have seen a rise in the groundwater levels in the vicinity,” Abhay said. 

However, with a low implementation rate of RWH, Bengaluru seems to have missed an opportunity to improve its water security. Experts estimate that Bengaluru utilises only 10% of the rainwater it receives, and point to huge gaps in infrastructure. 

“It’s a myth that we should get heavy rains to collect water through RWH systems. We just need the infrastructure. Even low to moderate rainfall will help us go a long way,” said Vishwanath S, a water conservation expert. 

He suggested creating more recharge pits to ensure that the rainwater helps improve the groundwater levels. 

Vishwanath estimates that Bengaluru has put only 10% of the rains to use. The remaining 90% is just left to drain away. 

Data from the Bangalore Water Supply and Sewerage Board (BWSSB) shows only 1.8 lakh out of the 19 lakh eligible properties in Bengaluru have installed rainwater harvesting systems. 

The BWSSB says penalising households that have not implemented RWH systems has had little impact. 

“We collect nearly Rs 1 crore in fines every month. People are okay with paying fines but aren’t ready to implement the RWH system,” a senior BWSSB official lamented. “There is nothing much we can do unless there is a mindset shift.” 

Another official called attention to a bigger problem — not everyone who has installed RWH is making the best use of it. 

“Many people are still not prepared to accept that rainwater can be used for all non-potable purposes. While they instal RWH systems to comply with the law, many tend to direct the harvested rainwater water to stormwater drains,” the official said. “This makes the entire system useless.” 

Every drop counts

In 2011, the government mandated RWH for new houses built on plots 60x40 feet or larger. 

In 2021, RWH was made mandatory for new constructions on 30x40 feet sites. The rule for 60x40 ft and larger plots was enforced retrospectively. 

Following the mandatory orders, BWSSB conducted a survey of constructions of 60x40 ft sites and found out that nearly 63,000 properties were to install RWH. Of this, close to 40,000 are yet to install RWH and have been paying the fine levied by BWSSB.