The focus of this paper is to provide an overview of analysis and optimal design of systems in which the system reliability is dependent upon the structure of the system (such as the layout of a water distribution system) and the size of the design components. Failure in these systems may occur due to a component failing independently (or at least assumed so) of the loading on the system. This, so called, mechanical failure can occur in hydraulic components such as pumps, turbines, pipelines, and valves. Depending upon the redundancy in the system the component mechanical failure can result in system failure. In addition, failure may occur depending upon the load on the system. Thus, it is desirable to quantify system of structure reliability as a function of both the mechanical reliability and system load. In the hydraulics area, efforts in structural reliability have proceeded primarily for water distribution systems including pipe networks and pump stations. Other potential application areas include water and wastewater treatment facilities and hydropower generation. Outside of the hydraulics area the concept of mechanical failure and system reliability has been studied in power and communication systems and engineering structure design.