My house plot is 7200 sqft. I would like to construct a rainwater harvesting system for the same and would like to ascertain the costs and materials required for the same. I would like to collect the water harvested in a underground tank of about 24 sq.ft

To construct rainwater harvesting system, what are the materials required to construct this and an approximate cost for the same? I would also like to learn more about subsidies or assistance offered by the Uttarakhand Government for the same.