The effect of roof surface area on the quality and quantity of rainwater runoff in the rainwater harvesting system

Abstract

Rainwater harvesting system is one of the alternative sources of clean water supply to be used during the dry season. The purpose of this research was to analyze the effect of roof area on the quality and quantity of rainwater runoff and determine the potential of rainwater runoff based on quality standards. The observation was conducted 2 different times and collected 23 samples of rainwater runoff from 11 different roof areas. Daily rainfall intensity data during the observation period were analyzed to estimate the quantity of rainwater runoff discharges from the rooftop catchment area. The results showed that parameters that meet the clean water quality standard are turbidity, iron, manganese, nitrate, and nitrite in both observation time. While the color, pH, TDS, and E. coli exceeds the clean water quality standard. The highest rainwater runoff volume was 20.59 m3 for the first week and the second week was 14.06 m3. In conclusion, the rooftop catchment area significantly affects the quantity and quality of rainwater runoff, and potentially be used as a clean water supply through a simple water treatment unit.