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.