supply when i am able to harvest rainwater which is sufficient enough for the entire year through wise usage shivakumar principal scientific officer and principal investigator of rainwater harvesting at the karnataka state council for science and technology located on the indian institute of science campus says shivakumar had studied bengalurus rainfall pattern for 100 years when he started building the house his invention popup filterin 2007 shivakumar who has handled rainwater harvesting for government buildings public places and institutions got a patent for his invention the popup filter the household is frugal in its water use consuming 400 litres daily against 6001000 litres used by any bengaluru family according to shivakumar a family of four needs 45000 litres of water to sustain for three months built on a 60 ft by 40 ft plot in vijayanagar in 1995 shivakumars house has two sumps and two overhead tanks to harvest rainwater though rainwater collected on the rooftop is pure and clean it needs to be filtered for suspended impurities like leaves bird droppings and dust it needs a person like shivakumar in every home to catch every rain drop suma says when we dug the borewell and found that water was available at just 120 feet she explains hence harvesting rain water would be a wise idea