Water Quality Based Multi-objective Optimal Design of Water Distribution Systems

Water distribution systems (WDSs) are one of the vital infrastructures in urban areas. The common objective considered in WDSs design is providing required water with the minimum construction cost. Less attention is paid to “water quality” as an objective in optimal design of WDSs. The aim of this paper is to include a water quality based objective in WDS design alongside other common objectives. For this purpose, the water quality reliability index developed based on “chlorine residual” and “water age”, is used. EPANET2.0 is applied for WDS simulation and ACO (Ant-Colony-Optimization) has been used as the optimization algorithm. Head-Driven-Simulation-Method (HDSM) is also considered. The proposed model is applied to Jahrom (a city in the south of Iran) WDS. The outputs show that the proposed model would result in less construction costs in comparison to the original design and 4–10 % of construction cost can be reduced depending on the considered objectives and selected optimal solution by managers and decision makers while the resulted solutions include high water quality reliability (ranging from 93 to 99 %). Also using HDSM method for hydraulic analysis of WDS instead of DDSM can lead to solutions with less construction cost (U$10,000 in average) and acceptable water quality reliability.