I was in Bhavnagar - Saurashtra, Gujarat and came across rooftop rainwater harvesting works implemented by (one more than 10 years ago) by Utthan with financial assistance from WASMO, along the same lines as what SACHETANA is attempting . These have strongly withstood the test of time and ALL of the rooftop rainwater tanks I saw (more than 120) were functioning and people were using this water exclusively for drinking and cooking. Here is a proof of concept idea which has withstood the test of time and which is ripe to be taken to areas of high fluoride and arsenic as one possible solution. Even in Gujarat this has unfortunately not happened in the fluoride affected areas at a scale which would benefit people.
Water security - rooftop rainwater harvesting in Gujarat by Utthan Add your say in the comments below!