Need simple techniques to purify borewell water for domestic purposes

Received over email.

We at Indus International School, are interested in providing safe portable water to a village which has around 1500 residents. We do not want to look at expensive means like the RO but do want to provide a simple low cost model to provide water. The source of the water for the village is from a borewell and there is an overhead tank where the water is pumped up. The same water is used for drinking and domestic use.

The village is near Sarjapur close to Bangalore in Karnataka and it comes under the same Panchayat. We will be glad if you could provide us some simple technique to go about this project.