Recently, there has been considerable emphasis on the state of decay in the nation's infrastructure because of its importance to society's needs and industrial growth. Water distribution systems are one of the many kinds of infrastructure systems amenable to higher levels of serviceability. Conventional design methods often fail to recognize, analyze, and account for, systematically, the effects of the various uncertainties that prevail in the design and operation of water distribution systems. Because of the existence of design and operation uncertainties, water distribution systems have an associated risk or probability of failure and an associated reliability or probability of not failing. The definition of failure can take on several meanings for a water distribution system, ranging from not meeting required pressure heads to the mechanical failure of a pipe or component. For water distribution systems, there are no universally accepted definitions for risk or reliability. The purpose of this paper is to review methods for risk and reliability evaluation of water distribution systems.