AWWA DSS65663

Aging water in distribution system storage facilities can have a detrimental impact on the quality of water delivered to customers. Excess water age can result in increased disinfection byproduct (DBP) formation and loss of chlorine residual. Utilities that use chloramination for final disinfection in efforts to minimize DBP formation often experience nitrification events in storage facilities as a result of extended water age. This paper presents a review of the types of typical distribution system storage facilities and the factors that influence the selection of storage facilities. It summarizes several case reports of distribution system water quality issues that have recently been reported in professional publications. The results from recent extended period simulation (EPS) water age and source trace analyses which were used to evaluate the impact of the operation, type, and location of storage facilities on distribution system water quality for a sample pressure zone are presented. These EPS analyses results show the relative impact that type and location of a storage facility can have on water quality in the distribution system. Includes 6 references, figures.