Rainwater harvesting in Greater Sydney: Water savings, reliability and economic benefits

Due to greater environmental awareness and mandatory water restrictions in many Australian cities, rainwater tanks have become popular in recent years. This paper investigates the water savings potential of rainwater tanks fitted in detached houses at 10 different locations in Greater Sydney, Australia. A water balance simulation model on daily time scale is developed and water savings, reliability and financial viability are examined for three different tank sizes, 2 kL, 3 kL and 5 kL. It is found that the average annual water savings from rainwater tanks are strongly correlated with average annual rainfall. Iris also found that the benefit cost ratios for the rainwater tanks are smaller than 1.00 without government rebate. It is noted that a 5 kL tank is preferable to 2 kL and 3 kL tanks and rainwater tanks should be connected to toilet, laundry and outdoor irrigation to achieve the best financial outcome for the home owners. The results from this study suggest that government authorities in Sydney should maintain or possibly increase the rebate for rainwater tanks to enhance its acceptance. (C) 2012 Elsevier B.V. All rights reserved.