Environmental Engineering Reference
In-Depth Information
efficiencies to minimize the
Cryptosporidium
levels in finished water. The
rule also includes disinfection benchmark provisions to ensure continued
levels of microbial protection while facilities take the necessary steps to com-
ply with DBP standards.
Stage 1 Disinfectants and Disinfection Byproducts Rule
The final Stage 1 Disinfectants and Disinfection Byproducts Rule applies
to community water systems and nontransient, noncommunity systems
(including those serving fewer than 10,000 people) that add a disinfectant
to the drinking water during any part of the treatment process. The final
Stage 1 Disinfectants and Disinfection Byproducts Rule includes the follow-
ing key provisions:
• Maximum residual disinfectant level goals (MRDLGs) for chlorine
(4 mg/L), chloramines (4 mg/L), and chlorine dioxide (0.8 mg/L)
• Maximum contaminant level goals (MCLGs) for four trihalometh-
anes (chloroform, 0; bromodichloromethane, 0; dibromochlorometh-
ane, 0.06 mg/L; bromoform, 0); two haloacetic acids (dichloroacetic
acid, 0; trichloroacetic acid, 0.3 mg/L); bromate (0); and chlorite (0.8
mg/L)
• Maximum residual disinfectant levels (MRDLs) for three disinfec-
tants (chlorine, 4.0 mg/L; chloramines, 4.0 mg/L; chlorine dioxide,
0.8 mg/L)
• Maximum contaminant levels (MCLs) for total trihalomethanes, a
sum of the four listed above (0.080 mg/L); haloacetic acids (HAA5)
(0.060 mg/L), a sum of the two listed above plus monochloroacteric
acid and mono- and dibromoacetic acids; and two inorganic disin-
fection byproducts (chlorite, 1.0 mg/L; bromate, 0.010 mg/L)
• A treatment technique for removal of DBP precursor material
The terms MRDLG and MRDL (not included in the SDWA) were created dur-
ing the negotiations to distinguish disinfectants (because of their beneficial
use) from contaminants. The final rule includes monitoring, reporting, and
public notification requirements for these compounds. This final rule also
describes the best available technology (BAT) upon which the MRDLs and
MCLs are based.
Subsequent Rules
Long-Term 1 Enhanced Surface Water Treatment Rule
Whereas the Stage 1 Disinfectants and Disinfection Byproducts Rule applied
to systems of all sizes, the Interim Enhanced Surface Water Treatment Rule
applied only to systems serving 10,000 or more people. The Long-Term 1
Enhanced Surface Water Treatment Rule strengthens microbial controls for
