In this paper we use the theory of planned behaviour (TPB) to identify the factors influencing people’s intention to conserve household water. A hierarchical multiple regression analysis of data from a survey of 401 individuals is conducted in a Spanish region. It confirms the explanatory power of the TPB model applied in two stages. Analysis of background factors shows that sociodemographic characteristics and knowledge and values about water and environment indirectly influence the intention to conserve household water. The results justify policies to promote knowledge and awareness, primarily targeting young people, and financial support measures, primarily targeting lower-income households.