In much of the western United States, reducing residential water use is a major source of water conservation, especially as population growth urbanizes agricultural land. Although estimates of the potential of conservation are useful, the experience of Australia provides a realistic target for residential water conservation. Although reliability of urban water use data is often questionable, it is clear that Australians use less water than Californians, with a similar climate, economy, and culture. Per capita usage is compared, and explanations for use differences are offered. If California had the same residential water use rates as Australia, it could have reduced gross urban water use by 2,600 GL (2.1 million acre-feet) in 2009 and potentially saved 1,800 GL (1.5 million acre-feet) for consumptive use by others.