AWWA WQTC65779

The Stage 2 Disinfectants/Disinfection Byproducts Rule (DBPR) will present a compliance challenge for many drinking water utilities. Consecutive drinking water systems will be particularly susceptible to these challenges. The American Water Works Association Research Foundation (AwwaRF) and the U.S. Environmental Protection Agency (USEPA) jointly funded Project # 3026, "Evaluation of Disinfection Practices for DBP and Precursor Occurrence in Consecutive Systems." The purpose of this nearly three year effort was to identify the factors which most significantly impact disinfection byproduct (DBP) formation in consecutive systems (CSs) and determine effective control strategies to reduce DBP formation in CSs. It was found that, regardless of the disinfection strategy, trihalomethanes (THMs) were the predominant DBP species formed in CS distribution systems. It was also observed that on average about 60 to 65 percent of the maximum DBP concentrations observed were formed in the water treatment plant and 75 to 80 percent were formed before the point of delivery to the consecutive system. This emphasizes the importance of treatment optimization in controlling DBPs, and in many cases may reduce the effectiveness of water age management strategies which were identified as best available technology (BAT) for consecutive systems in the Stage 2 DBPR. Includes reference, tables, figures.