In a boost to the water conservation mission, state environment secretary M L Meena on Thursday announced that any construction covering 20,000 square feet or more would require environmental clearance. "We have now made it mandatory for such construction to have rainwater harvesting facilities. This will ensure storage of water and recharging of ground water whenever necessary," said Meena.

Water experts have expressed concern over the rapid depletion of ground water table in Kolkata. The solution lies in tapping rainwater, they say. Besides, a systematic rainwater harvesting scheme would mitigate flooding in the city. "Experts have advised the city's civic authority to create stormwater reservoirs beside the roads so that the water, instead of being wasted down the drain or stagnating in pools, could be retained," said S Vishwanath, advisor of Arghyam, Bangalore based leading NGO working on water conservation.

According to the experts, the entire mankind would soon face serious crisis in potable drinking water with slow but steady depletion of fresh water. "If we do not change our way of life, nothing will be left for our next generation," said K R Gopinath, internationally acclaimed rainwater expert. Water, he said, is the most abused natural resource.