How supply system design can reduce the energy footprint of rainwater supply in urban areas in Australia

In Australia rainwater tanks are used in cities to reduce demand of mains water and increase the resilience of cities to drought. Rainwater is collected in a tank and supplied to a dwelling through a small pump. Typically the energy footprint for rainwater supply (in kWh/kL) is higher than for centralised water supply, but it can also vary markedly from dwelling to dwelling. This study aimed to understand how the design of the rainwater supply system from the collection tank to the household can reduce the energy consumption of pumping. Therefore we examined the operation of a range of system components for rainwater supply, such as pumps, switches and pressure vessels, in a controlled residential environment (a model house) to understand their impact on the energy footprint for rainwater supply in urban dwellings. Results show the impact of end uses, pump size and switches on the effectiveness of pressure vessels in reducing the energy footprint for rainwater supply.