Water harvesting- is the need of the hour to overcome the fascinating problem of water scarcity. Rainwater harvesting can be done both on a large scale such as watershed planning as well as on a smaller scale like rooftop rain water harvesting from individual houses.While the large scale water harvesting helps damming on water to sustain agriculture, rooftop water harvesting helps to meet the local needs of community. This book deals with a budgeting study with harvestable rooftop rainwater. To meet the potable water demands an effort was made to harvest rooftop rainwater from a workshop complex of soil and water conservation engineering, Tamilnadu Agricultural University Campus, Coimbatore. A filtering unit has been designed and installed at the site for the purpose. The designed structure is found to work well and is cost effective compared to corporation water supply and lorry loads of water supply.