Full Description

The proposed Stage 2 Microbial/Disinfection ByproductsRules are intended to reduce peak concentrations of disinfectionbyproducts (DBPs) in distribution systems and ensure safe drinkingwater for all consumers. Under this rule, water utilities conductingtheir initial distribution system evaluations (IDSEs) mustchoose sampling sites that capture peak DBP concentrations. Asthis study shows, however, selection of monitoring locations iscomplicated by the fact that trihalomethane (THM) and haloaceticacid (HAA) concentrations vary over time and space in a distributionsystem.Data were collected from five distribution systems that hadundergone DBP sampling for a variety of reasons, includingresearch studies, operational assessments, and the monitoringrequired for regulatory compliance. Analysis of these dataindicated that HAAs degraded in the distribution system, mostfrequently when chlorine or chloramine residuals were low.THM concentrations were generally high at these same samplelocations.The findings presented here should provide an impetus foradditional study of DBP fate and occurrence in distribution systemsas well as more extensive sampling efforts. The reduction inHAA concentrations observed in this study might have gone unnoticedin the typical utility sampling program. In addition to consideringmore extensive sampling, water suppliers may want toimplement study findings in the design of their IDSE studies orother distribution system investigations. Includes 22 references, tables.

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Edition: Vol. 97 - No. 2 Published: 02/01/2005 Number of Pages: 10 File Size: 1 file , 110 KB