BENGALURU: Bengaluru was solely dependent on rain-fed tanks for its water needs till the 1980s. Today, the city has grown bigger and water has to be pumped from 100km away from the Cauvery River, thus making it a costly affair for Bangalore Water Supply and Sewerage Board (BWSSB).
The state government pays `82 per km to pump the water. In comparison, the Delhi government pays `29 per km. Even with the hefty sum paid to transport water, bad distribution network has led to 509 million litres of water going waste daily.
In many other cities, a river is the major source of water. So when Bengaluru took shape as a city, its founders planned several lakes around the city to meet the water requirements of its residents.
As water levels in dams and reservoirs reduce, experts feel it is high time the lakes in the city are restored and alternative sources of water explored, including rainwater harvesting. But they have been ignored by the state government and authorities.
In his report ‘Matthondu Cauvery’ submitted to the state government last year, urban expert Ashwin Mahesh explains how lakes are substantial in catering to water requirements. He said, “There are lakes within the Bruhat Bengaluru Mahanagara Palike (BBMP) limits as well as Bangalore Metropolitan Region Development Authority (BMRDA).
While BBMP covers just over 750 sqkm, BMRDA covers ten times the size of BBMP. Both these regions receive roughly the same amount of rainfall. Together, we might gather water which can be more than what we receive from Cauvery.”
He added, “Harvesting just 10 per cent rainwater in Bangalore Metropolitan Region will increase water supply in the region by nearly 100 per cent. All we need to do is improve the watersheds to maximise the collection of rainwater and determining the piping and pumping needed to tap these new sources.”
He further said, “Around 4,000 people can be supported with each acre of a lake. So, 2,000 acres of lakes need to be used to serve the entire 8 million people who will be added to the region in the next 20 years.”
City’s growing needs
The first official water supply to the city was from the Hesaraghatta reservoir on the Arkavathy River, a tributary of Cauvery. With rapid expansion of the city, Bengaluru became solely dependent on Cauvery river by 1980s. At present, Bengaluru requires 1,450 million litres per day (MLD) and about 19 tmcft of water per year from Cauvery alone.
Noted environmentalist A N Yellappa Reddy said, “It is possible to make use of lakes for the city’s water needs by using wetland technology. There are several bigger lakes on the periphery of Bengaluru and I have pointed out the need of making use of these lakes. There are several spots with potential to trap water. At least 300 MLD of water can be generated from them.”
Voicing similar opinion, urban expert R K Misra said, “Lakes should be used as that was the purpose of its construction. But before that sewage should be diverted from the lake. Then we need to pump them to industrial areas so that the burden of Cauvery water comes down.”
On the contrary, A R Shivakumar, Principal Scientific Officer and Principal Investigator, Rainwater Harvesting, Karnataka State Council for Science and Technology, said given the pollution levels in lakes it is a difficult task to convert them into a source of drinking water. He said that it can only be done if treated water is let into lakes. “That can be done in the long run, but what is required immediately is water conservation measures, including rainwater harvesting, to deal with the current crisis,” he said.