Water Quality of Rooftop Rainwater Harvesting System (MyRAWAS)

Abstract

Prolonged drought, population growth and water demand for various purposes have increased the water scarcity issue. To overcome this issue, a rainwater harvesting system can be utilized as an alternative for clean water supply. A rainwater harvesting system is a method of collecting rainwater from man-made surfaces such as rooftops and constructed surfaces and can be used for various sectors including household, agricultural and commercial. This study was conducted to determine the quality of rainwater harvested collected directly from rooftop. The quality of the rooftop rainwater was taken in three consecutive months and the water quality for before and after treatment was measured and compared. Commercial activated carbon was used to treat the rainwater obtained from the rooftop. The water quality was compared with the Water Quality Index (WQI) and the National Water Quality Standards (NWQS). The parameters involved are pH, temperature, conductivity, dissolved oxygen (DO), total suspended solids (TSS), ammoniacal nitrogen (NH3-N), biochemical oxygen demand (BOD), chemical oxygen demand (COD),E.coli and total coliform bacteria. The results showed that the total value of WQI before and after treatment was 86.3 8.963 and 87.6 2.081, respectively. Positive correlations were found for parameter NH3-N, COD and pH, while paired T-test showed a significant in the COD and the presence of bacteria. Total Coliform is still at a safe level by NWQS with the average value and the standard deviation for before and after treatment were 38.11 13.960 cfu/ml and 10.33 6.671 cfu/ml, respectively.