Rainwater Harvesting System (RWHS) is a technique of water collection, which has been used since ancient times. A simple affordable, technically feasible and socially acceptable safe drinking water supply system in difficult geo-hydrological areas is very much in demand. RWHS can be considered as a probable solution of drinking water crisis in arsenic affected areas, saline zone in the coastal areas and areas prone to declining water table etc. Here, we have analyzed the rainfall characteristic of Bangladesh. In Bangladesh 85 percent of its annual rainfall during the monsoon and the average...