即将出台的消毒剂/消毒副产品（D/DBP）规则将包括一项要求，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；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。在美国各地不同水域进行的测试表明，一些水域将能够满足进水TOC去除标准，并且可以使用jar测试来确定符合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），该点可用于请求替代TOC去除性能标准。

The upcoming Disinfectants/Disinfection Byproducts (D/DBP) Rule will include 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; however, systems can demonstrate the need for alternative TOC removal performance criteria based on jar testing. Tests in various waters throughout the United States show that some waters will be able to meet influent TOC removal criteria and that jar testing can be used to determine a means of complying with the DBP precursor removal criteria. In other waters, however, the jar test will be needed to determine a point of diminishing returns (i.e., less than 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.