Maximize Revenue Generation, Minimize Potable Water Flushing, Optimize Distribution Water Quality for Areas Impacted by Reclaimed Water Service

Potable water utilities are facing increasedchallenges to water quality in the distri-bution system. These challenges come in several forms. The upcoming Stage 2 Disin-fection Byproduct Rule will result in more stringent monitoring and trihalomethane and haloacetic acid levels. Maintaining minimum disinfectant residuals, preventing bacteriolog-ical positive occurrences, preventing nitrifica-tion, and meeting increased customer quality expectations are additional challenges. The enemy of distribution system water quality is time. Water quality degrades with time. Chlorine residuals decay and disinfec-tion byproducts (DBPs) form as water age in-creases. With the advent of separate reclaimedwater distribution systems,utilities are facing a setback in efforts to minimize water age: Separate, dual reclaimedwater systems eliminate irrigation de-mands on a potable water system, which inher-ently increases water age in the system. Also, most potable distribution systems are sized for fire flows, meaning that there are significantly oversized pipes for non-irrigation potable demands—a situation that can cause significantly high water ages in parts of the dis-tribution system. Utilities are having to in-crease flushing efforts in areas where dual distribution systems have been implemented. To comply with DBP regulations, many potable water utilities are planning to switch or already have switched to chloramine disin-fectant to maintain a residual in the distribu-tion systems. High water ages in chloramine systems have created chronic water quality is-sues such as taste, odor, and nitrification that have required elevated distribution flushing quantities and efforts (Reed, 2006 and Riera, 2006, AWWA, 2006). The increased flushing quantities that sometimes must occur in drought/water re-striction periods can result in significant lost revenue and public relations issues. Methodology The concept behind this approach is to use select existing potable water customers to help improve potable water distribution qual-ity. For the purposes of this article, the con-cept will be referred to as the Water Quality Optimization (WQO) concept. The method-ology for the WQO concept is as follows