Recently, various studies have been conducted to optimize the pump operation scheduling and/or the pump/tank size minimizing the
system cost of water distribution network. Prior to that, it is important to understand the sensitivity of pump/tank size on the system cost
and overall water quality. Here, we have performed the sensitivity analysis to investigate the effect of pump/tank size on the economic
cost (construction and operation) and water quality (water age). The analysis was applied on a real, large-scale water transmission
network currently operating in South Korea. The results revealed that the pump/tank size has a strong influence on system construction/
operation costs. Especially, the tank size has a significant effect on the system-wide water quality. In the case of applied networks, the
operating cost decreases as the capacity of the facility increases, but the design cost increases. Using a sensitivity analysis, a suitable
range of pump/tank size could be suggested to minimize costs and stabilize the water quality at the same time prior to a system design.