Rainwater harvesting still slumbering in City

Rainwater harvesting still slumbering in City
Deccan Herald

The luke-warm response to the process is attributed to subsidised water supply, and lack of awareness.

It may well be the panacea for some of the water woes in Bangalore City. But rainwater harvesting is yet to receive its due merit.

Currently, less than one per cent of the estimated 12.5 lakh houses within Bangalore Mahanagara Palike (BMP) limits have adopted this measure – one that can not only address problems of urban flooding and water scarcity, but also contribute to groundwater recharge.

But why isn’t IT City backing this measure? Especially when BMP has made rainwater harvesting (RWH) mandatory for houses built after July 2004 and has warned that occupational certificates will not be issued to those violating norms; when it has offered a subsidy of Rs 1,000 on water bills for the first 5,000 owners of old buildings who adopt RWH?

After the July 2004 mandate by the BMP, 1,491 building plans were sanctioned with RWH facilities. Of these, only 73 sites have implemented the measure till date, while verification on plan progress have been done on 284, said BMP Engineer-in-Chief P K Sreehari.

When questioned on the remaining numbers, he said more time (around 18 to 24 months) would be required to complete the construction, before BMP can check on implementation.

“In case of non-conformity, owners of these houses will not be given occupational certificates,” he said, assuring that adherence to norms would be ensured strictly. According to RWH supporters, the luke-warm response is due to the highly subsidised domestic water supply, lack of awareness and a perception that the process is expensive.

Explaining statistics behind RWH, Vishwanath says most floods in cities occur because the rainwater runoff from each site goes up by a factor of 4 to 9 depending on the built-up area on the site. “For example, if 100 litres of rain fell on a site, about 10 litres would runoff when it is unbuilt. But after it is built, the runoff could be as high as 90 litres,” he says.

It is still a long way to go, when people would ask for the services of rainwater harvesting at the ring of the telephone, like they do for electricity.



SOLUTIONS

*Average rainfall in Blore centre: 15 per cent

*Nearly 20 % of City’s water requirement can be met

*What falls as rain on City: Equivalent of 3,000 MLD

*Cauvery IV Stage scheme Phase II target: 1,500 MLD

*A study in Chile over 2 years showed that there can be 10-20 % reduction in stormwater volume and 20-40 % reduction in stormwater peak outflow following RWH implementation.