拟议的第2阶段微生物/消毒副产品 这些规定旨在降低消毒的峰值浓度 分配系统中的副产品（DBP），确保安全饮用 为所有消费者提供水。根据这条规则 他们的初始分配系统评估（IDSE）必须 选择捕获DBP峰值浓度的采样点。像 然而，这项研究表明，监测地点的选择是非常困难的 由于三卤甲烷（THM）和卤乙酸 酸（HAA）浓度随时间和空间的分布而变化 系统 数据收集自五个有 由于各种原因进行DBP采样，包括 研究、运营评估和监控 符合法规要求。对这些数据的分析 表明HAAs在配电系统中退化，大多数 通常在氯或氯胺残留量较低时。 在这些样品中，THM浓度通常较高 位置。 这里介绍的研究结果应该会推动 配电系统中DBP命运和发生的补充研究 以及更广泛的抽样工作。减少 本研究中观察到的HAA浓度可能没有引起注意 在典型的公用设施采样程序中。除了考虑 水供应商可能希望进行更广泛的采样 在IDSE研究设计中实施研究结果，或 其他分销系统调查。 包括22个参考文献和表格。

The proposed Stage 2 Microbial/Disinfection Byproducts Rules are intended to reduce peak concentrations of disinfection byproducts (DBPs) in distribution systems and ensure safe drinking water for all consumers. Under this rule, water utilities conducting their initial distribution system evaluations (IDSEs) must choose sampling sites that capture peak DBP concentrations. As this study shows, however, selection of monitoring locations is complicated by the fact that trihalomethane (THM) and haloacetic acid (HAA) concentrations vary over time and space in a distribution system. Data were collected from five distribution systems that had undergone DBP sampling for a variety of reasons, including research studies, operational assessments, and the monitoring required for regulatory compliance. Analysis of these data indicated that HAAs degraded in the distribution system, most frequently when chlorine or chloramine residuals were low. THM concentrations were generally high at these same sample locations. The findings presented here should provide an impetus for additional study of DBP fate and occurrence in distribution systems as well as more extensive sampling efforts. The reduction in HAA concentrations observed in this study might have gone unnoticed in the typical utility sampling program. In addition to considering more extensive sampling, water suppliers may want to implement study findings in the design of their IDSE studies or other distribution system investigations. Includes 22 references, tables.