Effects of Redesign of Water Systems for Security and Water Quality Factors

Water distribution systems are typically designed based on hydraulic and cost considerations. In the United States, most urban water systems are looped systems with large pressure zones that serve customers in regions of different elevation. In the United Kingdom, water distribution systems are frequently further subdivided into zones of several thousand connections called district metering areas (DMAs) in order to track and control water leakage. In two case studies, starting with existing large looped water system designs, the current systems are redesigned to: (1) approximate a typical DMA design; and (2) provide additional control and isolation capability in order to improve the water security of the system. The systems are then compared in terms of four metrics: (1) fire flow; (2) water age; (3) water security; and (4) reliability. Though the results of the analysis may not necessarily be generalized beyond the case study examples, the methodology provides a mechanism for evaluating alternative water system designs, and provides insight into the effects of water security criteria on system design.