Section 611.380  General Requirements

a)         This Subpart I Constitutes NPDWRs

1)         This Subpart I establishes standards for a CWS supplier or an NTNCWS supplier adding a chemical disinfectant to its water in any part of the treatment process modifying its practices to comply with MCLs and MRDLs in Sections 611.312 and 611.313, respectively, and complying with the treatment technique requirements for DBP precursors in Section 611.385.

2)         This Subpart I establishes standards for a transient non-CWS supplier using chlorine dioxide as a disinfectant or oxidant modifying its practices to comply with the MRDL for chlorine dioxide in Section 611.313.

3)         MCLs for TTHM and HAA5 and treatment technique requirements for DBP precursors limit the levels of known and unknown DBPs that may have adverse health effects.  These DBPs may include chloroform, bromodichloromethane, dibromochloromethane, bromoform, dichloroacetic acid, and trichloroacetic acid.

b)         This subsection (b) corresponds with 40 CFR 141.130(b), which recites past implementation deadlines.  This statement maintains structural consistency with the corresponding federal rules.

c)         Qualified personnel complying with 35 Ill. Adm. Code 681 must operate the water system for each CWS or NTNCWS supplier subject to subsection (a).

d)         Controlling Disinfectant Residuals.  Notwithstanding the MRDLs in Section 611.313, a supplier may increase residual disinfectant levels of chlorine or chloramines (but not chlorine dioxide) in its distribution system to a level and for a time necessary to protect public health, to address specific microbiological contamination problems caused by circumstances such as distribution line breaks, storm run-off events, source water contamination events, or cross-connection events.

BOARD NOTE:  This Section derives from 40 CFR 141.130.

(Source:  Amended at 47 Ill. Reg. 16486, effective November 2, 2023)