Study on Correlation Among Roof Area, Reservoir Volume and Domestic Water Availability from Rainwater Harvesting in East Part of Surabaya

This research investigates the application of rainwater harvesting system as clean water source alternative in East Surabaya. The rainwater harvesting system performance is simulated to obtain the water availability for typical residential lot size in the study area. The water demand in this study is assumed as three scenarios. Reservoir volume is calculated based on available area for typical lot types in Indonesia. Daily and monthly rainfall data is used to simulate the rainwater harvesting system performance and to obtain the correlation between roof area, reservoir volume and water availability. Simulation results show that 90% water availability is achieved by the system for lower water demand of 20 l/person/day. The reservoir volume needed to hold water in annual, monthly, and daily simulations, respectively, is 15, 12 and 10.5 m3. The correlation between roof area and reservoir volume with water availability is also developed. The ratio between the volume of the reservoir used to hold water and the total water demand for one year is 34–51%. Even though the rainwater harvesting system could give a 90% water availability, there will be a deficit of water in dry season. Therefore, a large reservoir is needed to fulfil the water requirement in the dry season.