拟议的消毒剂/消毒副产物（D/DBP）规则包括一项要求，即使用常规处理的地表水系统必须去除DBP前体（以总有机碳（TOC）衡量），此外还必须满足D/DBP本身的标准。TOC去除标准基于进水TOC和碱度（称为步骤1）；然而，系统可以证明需要基于jar测试的替代TOC去除性能标准（称为步骤2）。根据美国各地的各种源水进行的测试表明，一些水域将能够满足第一步TOC去除标准，尽管不需要进行第二步分析，但jar测试可用于确定符合DBP前体去除标准的方法。然而，在其他水域，需要进行jar试验，以确定收益递减点（即增量剂量为10 mg/L明矾时，TOC去除量小于0.3 mg/L），以用于请求替代TOC去除性能标准。 包括19个参考文献、表格和图表。

The proposed Disinfectants/Disinfection By-Products (D/DBP) Rule includes a requirement that surface water systems using conventional treatment must remove DBP precursors--as measured by total organic carbon (TOC)--in addition to meeting standards for the D/DBPs themselves. TOC removal criteria are based on influent TOC and alkalinity (referred to as step 1); however, systems can demonstrate the need for alternative TOC removal performance criteria based on jar-testing (referred to as step 2). Tests based on various source waters throughout the United States show that some waters will be able to meet step 1 TOC removal criteria and that although step 2 analysis is not required, jar testing can be used to determine means of complying with the DBP precursor removal criteria. In other waters, however, jar tests will be needed to determine a point of diminishing returns (i.e., <0.3 mg/L TOC removal for an incremental dose of 10 mg/L alum) that can be employed in requesting alternative TOC removal performance criteria. Includes 19 references, tables, figures.