Effect of Rainwater Harvesting on Residential Water Use: Empirical Case Study

Rainwater harvesting (RWH) through household rainwater tanks has been increasingly recognized as a supplementary source of water in most urban cities. Previous studies indicated wide variations in annual water saving on residential water consumption. This study aimed to examine the factors causing these variations on the calculated savings of residential water use. The study involved the analysis of water consumption data collected by Yarra Valley Water (YVW) for 50 households with rainwater tanks and 50 without in Greater Melbourne, Australia. The results initially indicated an average annual saving of more than 4,600 L per year for an average household of 3.1 people; however, after considering seasonal variations, the estimated average potable water saving was more than 9,700 L per year. Further analysis revealed that properties without garden watering received more water saving than properties with garden watering (34,400–5,600 L per year, respectively). The results of this study are envisioned to lead to a better understanding of the effect of seasonal variations and local site conditions on the potential of RWH in integrated urban water management.