In this document, EPA is finalizing maximum residual disinfectant level goals (MRDLGs) for chlorine, chloramines, and chlorine dioxide; maximum contaminant level goals (MCLGs) for four trihalomethanes (chloroform, bromodichloromethane, dibromochloromethane, and bromoform), two haloacetic acids (dichloroacetic acid and trichloroacetic acid), bromate, and chlorite; and National Primary Drinking Water Regulations (NPDWRs) for three disinfectants (chlorine, chloramines, and chlorine dioxide), two groups of organic disinfection byproducts (total trihalomethanes (TTHMs)--a sum of the four listed above, and haloacetic acids (HAA5)--a sum of the two listed above plus monochloroacetic acid and mono-and dibromoacetic acids), and two inorganic disinfection byproducts (chlorite and bromate). The NPDWRs consist of maximum residual disinfectant levels (MRDLs) or maximum contaminant levels (MCLs) or treatment techniques for these disinfectants and their byproducts. The NPDWRs also include monitoring, reporting, and public notification requirements for these compounds. This document includes the best available technologies (BATs) upon which the MRDLs and MCLs are based. The set of regulations promulgated today is also know as the Stage 1 Disinfection Byproducts Rule (DBPR). EPA believes the implementation of the Stage 1 DBPR will reduce the levels of disinfectants and disinfection byproducts in drinking water supplies. The Agency believes the rule will provide public health protection for an additional 20 million households that were not previously covered by drinking water rules for disinfection byproducts. In addition, the rule will for the first time provide public health protection from exposure to haloacetic acids, chlorite (a major chlorine dioxide byproduct) and bromate (a major ozone byproduct). The Stage 1 DBPR applies to public water systems that are community water systems (CWSs) and nontransient noncommunity water systems (NTNCWs) that treat their water with a chemical