Evaluation of water mixing characteristics in distribution system storage tanks

Distribution system storage tanks that are underutilized or have poor mixing characteristics are one of the challenges faced by many water utilities in maintaining water quality in their distribution systems. Computational fluid dynamics modeling, water temperature measurements, and chlorine residual measurements can be effective tools in predicting mixing characteristics inside storage tanks. This article demonstrates how these tools can be used to determine mixing characteristics within storage tanks, identify tanks with poor mixing characteristics (and thus the greatest potential for water quality deterioration), and help modify designs to improve mixing characteristics. Field data are presented to demonstrate how design modifications improved water mixing characteristics in an operating storage tank.