Water distribution systems are changing continuously as a result of growth or decline of water demand, changes in water quality, aging infrastructure, etc. An assessment of the distribution system must be based upon a set of measures analyzed over an extended period of time. In this paper, the assessment of distribution system performance is expressed in terms of the level of service received by customers of the system. All water systems should assess the performance of their distribution systems using the performance criteria and performance parameters developed in this study. Solutions to performance deficiencies of parameters such as structural performance, hydraulic performance and water quality performance are interlinked. It is recommended that all water systems should conduct such a comprehensive assessment of the distribution system annually.