Rooftop rainwater harvesting potential for a domestic purpose using samsamwater, case of Jimma University Institute of Technology, Ethiopia

Abstract

\n The key sources of water supply are rainwater, underground water and surface water. Rooftop rainwater harvesting is a technique through which the rain is captured from the roof catchments. The objective of this study was to investigate rooftop rainwater harvesting potential for domestic purposes using a samsamwater tool. This can be used in dry and wet seasonal situations based on the roof size and population density, which plays a crucial role in socioeconomic development and keeping community school welfare. Rooftop rainwater harvesting is the most reliable, easiest to access, and suitable source for water supply. This study was carried out from June 2018 to December 2019 based on a case study of three Jimma University Institute of Technology Kito furdisa campus. Since then, rainfall data, rooftop catchment, water consumption and water demand data have been used as inputs. Based on the findings, the annual rainfall is 1846 mm. The total roof size of the school is 888.32 m2 and almost the entire age of the building ranges between 5-15 years. It has been constructed of galvanized iron in which its run off coefficient is estimated at 90%. The collected data has been analyzed using different tools, including the Samsamwater RWH model, and SPSS statistics version 22. As a result, the volume of harvested rainwater was 12,826 m3/yr., which covered all non-potable water needs for 14,458 of the school population. The total yearly water requirement for a working day (182 days) and working days plus no working days (365 days) of the school is 18,606.72 and 26,759.47 m3/yr. respectively. The reliability of harvested rainwater from the rooftop for the community school can meet about 63.4 % of the water scarcity reduced by feeding for (365days). Whereas the reliability of rainwater-harvested potential is, 82% of water demand can be met by considering the schedule of working days (9 months). The average reliable for the study area is greater than 72.6% of water demand.