Abstract: This paper reports on research using geodemographic approaches to examine the dimensions of household water use in South East Queensland. In 2005, a lengthy drought and high population growth was placing increasing pressure on urban water supplies. In response, the Queensland State Government implemented a suite of remarkably effective demand-side policy measures: from 2005 to 2008, average household water use dropped from 300 to 130 Litres Capita Day. The paper reports on Phase One of a research program, which used Geographic Information Systems, Principal Components Analysis, and other statistical methods to explore the spatial, socio-demographic and structural determinants of household water use. The most significant variables found to predict high water use at the Census Collection District scale were lot size, children at school and mortgages. This spatial analysis will inform Phase Two, which uses a behavioural science framework, based on an extended Theory of Planned Behaviour, to investigate individual householder attitudes and behavioural change in response to policy measures. Understanding how this behavioural change occurred on such a mass scale, and over such a short period, is potentially of great significance; the results of this research could enable finer targeting of demand-side policy, and help maintain lower levels of water use.