 In Australia, there are no quantitative performance targets for rainwater tanks, such as size of tank or targeted reductions in potable water demand, in policies or guidelines.The various guidelines provided by state governments however, do advise that rain water tanks be designed to provide a reliable source of water to supplement mains water supply, and maintain appropriate water quality.The use of rainwater tanks should consider issues such as supply and demand, water quality, stormwater benefits (volume is reduced), cost, available space, maintenance, size, shape and material of the tank.