Abstract The paper proposes a model that evaluates the risk of a water distribution system looking to three aspects, namely; available pressure, water demand, and water quality. Three failure modes were considered for examining the risk. The risk has been defined imitating the original definition of Hashimoto's vulnerability, and expressed as the failure magnitude with respect to each level of service provided at a certain location and during a certain period of time. When assessing the risk rather than focusing on just one aspect the overwhelming task has been used for better evaluation and mitigation of the overall risk. The model was developed using Analytic Hierarchy Process (AHP) coupled with Fuzzy Set Theory. The first assigns weight for each kind of risk that reflects its relative importance among the other risks. The second is a fuzzy building methodology that employs the assigned weight and others external information to harmonize all risks into a unique platform and allow one to obtain the system's overall risk. The model has been implemented and tested through the real network of Matera city.