Rainwater harvesting potential in Sydney : are we harvesting enough?

Abstract

Rainwater harvesting has become popular in Australian urban areas due to water restrictions, greater environmental awareness, government regulations and incentives for installation of rainwater harvesting systems. It can provide non-potable water to meet various needs such as toilet flushing, laundry, gardening and car washing. In peri-urban and rural areas of Australia, rainwater is also used for drinking. In the urban areas, rainwater tanks are connected with water mains and hence users have no idea how much water they are saving due to having a rainwater tank. In this paper, rainwater harvesting potential in Sydney is investigated by developing a continuous simulation model that accounts for daily rainfall and water demands. The water savings and reliabilities for 3 kL, 5 kL and 7 kL tanks as well as 10 and 15kL are investigated and compared with BASIX requirements in New South Wales (NSW). It has been found that the currently recommended 3 kL tank size in NSW is unlikely to provide optimum water savings from a rainwater harvesting system. The findings of this study will be useful to recommend an appropriate tank size for Sydney, Australia.