Prime Minister Manmohan Singh today said the government cannot continue to subsidise the economic and commercial use of water."Providing free power to farmers has encouraged excessive use of pump sets and excessive drawing of ground water. If there is economic pricing of power, there would be some incentive for conserving ground water," he said at the National Congress on Ground Water."Water conservation and management could be better served through appropriate incentives and penalties... We cannot continue to subsidise the economic and commercial use of water," Singh said."There are related policies that must be corrected to ensure water conservation, especially ground water," he said."Human kind has not done enough to replenish, conserve and safeguard the sources of water supply... On the contrary, given the threat of climate change and global warming, we face the real prospect of reduced supply of water," Singh said."This threat is of particular concern to us in India since we have, since times immemorial, depended on glaciers for our water supply in this part of our subcontinent," he said.