Economics of rainwater tanks in multi-storied complexes in three cities of New South Wales, Australia

Rainwater tanks have emerged as an Australian icon of water conservation in recent years to meet the ever-increasing fresh water demand in Australian cities. There has been significant interest in rainwater tanks but their economic viability and efficiency in reducing town water demand to end-users has yet to be firmly established. This paper investigates the economic viability and town water reduction efficiency of rainwater tanks in multi-storied residential housing complexes in three cities of east coast New South Wales. Historical daily rainfall data was used to establish optimum rainwater tank size to achieve near 80% savings of main's water. This paper explores the economics of rainwater tanks of varying sizes to meet water savings of different levels and highlights the importance of life cycle cost analysis of rainwater tanks as a measure of safeguarding long-term viability of rainwater tanks, a vital component of Water Sensitive Urban Design.