Suggestions Invited For Large-Scale Rainwater Harvesting

If there is no rain, there is no water. Ground water is depleting. Floods are occurring easily because we individuals destroy the ecology. There is no proper community water bodies, before installing a rain water harvesting system in our houses, we should know how to save a tree and even if we need to build something, we can be clever and keep it safe and build anything without destroying it. There should be water tanks which is open in everyone's houses, so that rain water gets collected.