Householders in cities face water-related issues due to the increasing cost and restrictions in water use, especially during drought. They respond in many different ways, ranging from installing water efficient appliances, adopting water-saving behavior and implementing greywater reuse, to being water self reliant (off-mains supply). The latter approach should consider using only rainwater falling on the property boundaries, and if self-supply is from groundwater it should be derived from rainwater falling on the property. Therefore, sustainability depends on the annual rainfall, size of property and availability of storage for water to be used during periods without rainfall. In principle any house can be retrofitted to rely solely on rainwater, because technologies exist to treat subsequent wastewater to any quality desired for reuse. However, the energy requirement and investment needed may negate overall sustainability. Very few studies have assessed water use in households to determine whether relying solely on rainwater is practical or sustainable in the long-term. Three case studies in Perth, Western Australia are reported here, where water auditing has been used for sustainability assessment.