This study tested the explanatory power of Ajzen's (1991) theory of planned behavior (TPB), and a modified TPB model including perceived moral obligation (PMO) and perceived water right (PWR), to predict people's intentions to conserve water. The study had 244 government employees who participated. The TPB variables improved the prediction of intention to use less water, but were less successful in predicting intention to install water-efficient appliances. A significant interaction was found between attitude and subjective norm, suggesting that past studies have overlooked moderating effects in the TPB model. In addition to the TPB variables, PWR further improved the prediction of intention to install water-efficient appliances. Results also suggest that water-saving procedures should be differentiated into curtailment and efficiency procedures.