Water is an essential resource to society. Conserving water is an intrinsic part of human behaviour. Traditional water conservation approaches typically adopt command-and-control strategies that are restrictive, and do not always achieve long term sustainable water conservation. Understanding the causal mechanisms of behaviour that result in changes to an individual’s attitudes, desires, and motivations offers an alternative approach to conserving water. The nature of sustainable water conservation is revealed in three behavioural mechanisms: capability - the capacity to engage in conservation activities; opportunity - external conditions that enable behaviour to occur; and, motivation -internal factors that energise or direct behaviour.