Modeling of Rainwater Harvesting System

Sepaku District, located in Penajam Paser Utara Regency, East Kalimantan, Indonesia, faces a major challenge in providing clean water due to the limited availability of water sources. One of the alternative solutions that can be offered to overcome this problem is the application of rainwater harvesting technology using the Gama Rain Filter (GRF), designed to improve the quality of rainwater for non-domestic use. This study aims to simulate various scenarios of storage capacity to determine the duration of water availability in the rainwater harvesting installation. PowerSim software was used in this dynamic system modeling to simulate various scenarios of rainwater use. The variables influencing this model included rainfall, building roof area, storage capacity, and daily water consumption. This model considered three different scenarios of storage capacity: 1200 L, 2200 L, and 5500 L. This model helped illustrate complex cause-and-effect relationships within the water supply system and helped examine its impact on the efficiency of rainwater harvesting in meeting water demands. The software displayed technical data, water demand calculations, and potential rainwater supply based on historical rainfall data. The results of the simulation showed that rainwater harvesting technology significantly reduces reliance on groundwater sources and pipe water from the regional water utility (Perumdam) if it is effectively designed, properly applied, and well accepted by the community.