Analysis of Optimum Rainwater Tank Size in a Multi-building

Abstract

The size of rainwater storage tank is crucial to cost-efficiency of rainwater harvesting (RWH) systems and the optimum capacity is variable with the main purposes of RWH systems which determine the criteria used in calculation. In this research, four scenarios were analyzed to evaluate the differences of optimum tank sizing under different RWH springboards using a daily simulation and economic analysis in a multi-building. Results showed that with the criterion of maximum potable water saving percentage, the ideal capacity was 55m3. The best tank sizing was 85m3 with the criterion of maximum extent to reduce roof runoff but there was economic deficit. With the purpose to obtain the maximum financial savings the best size was 60m3 and the percentage of reduced roof runoff was 72.92%. When there was no saving and deficit, the ideal size was 75m3 and the percentage of reduced roof runoff was 91.15%.