NEW DELHI, Oct 3: President K R Narayanan today said India is facing an ``acute water crisis'', with some estimates indicating health costs of water pollution will wipe out the benefits of economic growth.Inaugurating a three-day national conference here on `The Potential of Water Harvesting', the President said experts had warned that the world is heading towards ``a water shock'' which might dwarf the oil crisis.For India, the shortage of water and its growing pollution had acquired the proportion of a crisis for the people, especially the poorest of the poor. ``The health costs of water pollution do not get factored into our economic calculations'', he added.Historically, Indians have been the world's greatest water harvesters, Narayanan said. He added a people's movement was needed to meet the growing water needs and protect water sources.Felicitating five rural engineers who had made a significant contribution to preserving and promoting water harvesting systems, the President said, ``Icongratulate them for their remarkable, notable and original work. They are our greatest teachers and even sophisticated scientists will have a lot to learn from them.'' The engineers are Chewang Norphel, who has devised an innovative method to make artificial glaciers in Leh to recharge water bodies, Magga Ram Suthar from Jaisalmer who digs `beris' (narrow deep wells), Ran Singh from Churu who makes `kundis' (covered tanks), Kunhikannan Nair of Kasargod who has perfected the art of making `surangams', narrow and deep tunnels in rock and Ganesan, a `neerkatti' or water manager from Madurai.The three-day conference, organised by the Centre for Science and Environment, is focussing on low-cost water harvesting techniques and their potential to meet local water needs in towns and villages.In his keynote address, CSE director Anil Aggarwal said it was ironical that India was doomed to turn into a nation of thirst when rain captured from just one to two per cent of its land with simple techniques couldprovide the 950 million people as much as 100 litres of water per person daily.If the right measures are not taken even now, the per capita availability of water in India in 2001 is expected to be half its 1947 level, he added.With over-exploitation and contamination of ground and river water bringing the country to the brink of a water crisis, we needed to turn to age-old techniques of rain and ground water harvesting, which essentially meant collecting and cleaning rain water where it fell, he said.Instead of continuing as the main water provider, the government should help efforts at community and household levels to collect and conserve water, as is being done in Chennai, Dr Aggarwal said.``It is a fallacy that the Telugu Ganga Canal can end the water crisis in Chennai, or Jodhpur can pin its hopes only on the Indira Gandhi Canal and Kanpur on the barrage on the Ganga. Most of these projects are environmental disasters and financially unsustainable. The answer lies only in learning from thelocal communities, the time-tested techniques of catching water where it falls,'' he added.