In times of crisis there are two things one can do: crib and cry or do something about it. When the groundwater in the industrial city of Coimbatore plunged to 300 m at some places four years ago, its corporate houses and residents opted for the second way out: they took matters into their hands.

All the eight natural water tanks in Coimbatore were silted and clogged with garbage following large-scale construction activity since 1998. The dried riverbed of the Noyyal, running alongside the city, was encroached upon and channels leading to it clogged. Low rainfall aggravated the problem. According to the Coimbatore municipal corporation's Citizens' Charter, the city's daily water supply shrunk a fifth. Agriculture, the main activity of the people in the suburbs, was affected.

"Water shortage was really acute; we decided to do something about it,' says Vanitha Mohan, executive director of Premier Instruments & Controls Ltd. This was when Siruthuli