Impacts of using rainwater tanks on stormwater harvesting and runoff quality

The popularity of rainwater use in Australia depends completely on the individual householder's preference. The quality of reticulated water supplies in major cities of Australia is far superior to water stored in rainwater tanks. However, due to persistent drought and the implementation of stringent water restrictions, cities such as Melbourne have encouraged the use of rainwater harvesting within the property. The benefits of trapping stormwater within a property and using it effectively also reduce polluted runoff excess reaching receiving water. The study reported herein focuses on the effectiveness of rainwater tanks as a potential water sensitive urban design element used to manage stormwater using the MUSIC model. The study shows that the installation of a 3 kL tank reduces hydraulic loading by 75%, Total Suspended Solids by 97% Total Phosphorous by 90% and Total Nitrogen by 81% if the rainwater stored in the tank is used to meet the indoor demand (toilet flushing and laundry use) as well as the outdoor demand (garden watering).