Customer satisfaction is an important goal in total quality management. In order to meet this goal, it is necessary to use an evaluation model to measure customer satisfaction. This paper proposes an evaluation model for measuring the customer satisfaction level in a water supply domain. Some important criteria such as water quality, water quantity, responsibility of the company, etc. are distinguished and used in the proposed model. To integrate all of these criteria in a unit index, the analytic hierarchy process technique is used. The proposed model integrates customer opinions in a unit index to measure the customer satisfaction level. To evaluate the effectiveness and efficiency of the proposed model, Hamedan Water Company is studied as a case study. The results show that the proposed model can be used as a useful tool for analyzing customer satisfaction levels in water supply domains for other companies. The proposed model also distinguishes company strengths and weaknesses in the field of customer satisfaction.