Costs & vendor contacts for implementing rainwater harvesting in W.Bengal

I am a Rotarian belonging to Dist 3291 West Bengal. In a village about 50 km from Kolkata we are planning to introduce Rain Water Harvesting. I know W.Bengal has adequate rain & has many ponds. The problem is safe drinking water.We would like to improve the quality & quantity of water for the villagers.   How do we go about & is there any institution in W Bengal which can give us an idea about the cost involved?

Dr Neeraja Rateria