Rain tanks or reticulated water supply

Reticulated water supply systems, standard practice in urban areas, suffer from water losses due to leaks and pipe bursts, and for satisfactory service need a high level of investment and intervention. Due to growing concern over future water shortages in urban areas, localized measures such as rain tanks are being widely promoted as a more sustainable alternative: they can promote improved water management through behavioural changes, thereby reducing the overall consumption. The two systems, however, vary widely in terms of scale, useful life, and level of service, and it is impossible to assess accurately the relative long-term sustainability performance without a detailed life-cycle analysis. Using the results of a life-cycle study of reticulated supply and rain tanks for urban houses in Auckland, New Zealand, which concentrates purely on the environmental performance, this paper argues that rain tanks may not be the most sustainable option in all situations - while rain tanks are better in some situations, reticulated supply is better in others.