Rainwater harvesting is an innovative and a suitable alternative approach of water supply that can be used by anyone. Rainwater harvesting captures, diverts, and stores rainwater for later use. It is a well known fact that during summer season there is a huge scarcity of water in northern regions of India and as such implementing rainwater harvesting would be beneficial because it would reduce demand on existing water supply reduces run-off, erosion, and also contamination of surface water. A rainwater harvesting system can range in size and complexity. All systems have basics components, which include a catchment surface, conveyance system, storage, distribution, and treatment. As such, we discuss in this paper about the prospects and possibilities of rainwater harvesting in Shimla region of Himachal Pradesh, which experience water shortages in summer periods due to increase in population and also climatic conditions. The result of our study shows that judicious storing of rain water all round the year and not only summer can be stored without incurring any significant losses. Further, the study shows that the sanitation water requirements for a family can be met for two months with storage of rainwater for one single month only. Further, the construction pattern of houses in Shimla (sloped roof structures) already provides an advantage in storing rainwater efficiently. The non-dimensional design parameters can be applied for any place which experiences a scarcity of water. The paper also presents a simple benefit-cost ratio for the designed rainwater harvesting system.