Spatial Variability of Reasonable Government Rebates for Rainwater Tank Installation: A Case Study for Adelaide, Australia

Abstract

Rainwater harvesting is a sustainable alternative water source in urban and suburban areas. So government authorities are encouraging the households to install rainwater tank in their premises by providing the subsidies. However, with increasing demand and financial constraint many government authorities are struggling to maintain such subsidy. As such, a prudent and optimum government rebate needs to be derived. This chapter presents the spatial variability of reasonable government rebates for rainwater tanks installations with a case study for an Australian coastal city, Adelaide. It is shown that significant variations among the regions are expected in regards to rainwater savings, even with the same tank size, same roof connection and same rainwater demand. Providing a double-sized tank and double-sized roof is likely to increase the savings only up to 1.19 times and 1.78 times respectively. It is found that the payback periods of total rainwater tank related costs widely vary depending on region, tank, roof and demand scenario; a variation from 15 to 79 years without government rebate is expected. However, with reasonable government rebates these payback periods can be brought down to 8 years. To optimise government’s spending a variable rebate scheme can be introduced based on the current findings.