Section 611.950  General Requirements

a)         The requirements of this Subpart X constitute national primary drinking water regulations.  These regulations establish requirements for filtration and disinfection that are in addition to criteria under which filtration and disinfection are required under Subpart B.  The regulations in this Subpart X establish or extend treatment technique requirements in lieu of maximum contaminant levels for the following contaminants:  Giardia lamblia, viruses, heterotrophic plate count bacteria, Legionella, Cryptosporidium, and turbidity.  The treatment technique requirements consist of installing and properly operating water treatment processes that reliably achieve the following:

1)         At least 99 percent (2-log) removal of Cryptosporidium between a point where the raw water is not subject to recontamination by surface water runoff and a point downstream before or at the first customer for filtered systems, or Cryptosporidium control under the watershed control plan for unfiltered systems; and

2)         Compliance with the profiling and benchmark requirements in Sections 611.953 and 611.954.

b)         Applicability of the Subpart X Requirements.  A supplier is subject to these requirements if the following is true of its system:

1)         Is a public water system;

2)         Uses surface water or groundwater under the direct influence of surface water as a source; and

3)         Serves fewer than 10,000 persons.

c)         This subsection (c) corresponds with 40 CFR 141.502, which includes a past implementation date.  This statement maintains structural consistency with the corresponding federal provision.

d)         Subpart X Requirements.  There are seven requirements of this Subpart X, and a supplier must comply with all requirements that are applicable to its system.  These requirements are the following:

1)         The supplier must cover any finished water reservoir that the supplier began to construct on or after March 15, 2002, as described in Section 611.951;

2)         If the supplier's system is an unfiltered system, the supplier must comply with the updated watershed control requirements described in Section 611.952;

3)         If the supplier's system is a community or non-transient non-community water system the supplier must develop a disinfection profile, as described in Section 611.953;

4)         If the supplier's system is considering making a significant change to its disinfection practices, the supplier must develop a disinfection benchmark and consult with the Agency for approval of the change, as described in Section 611.954;

5)         If the supplier's system is a filtered system, the supplier must comply with the combined filter effluent requirements, as described in Section 611.955;

6)         If the supplier's system is a filtered system that uses conventional or direct filtration, the supplier must comply with the individual filter turbidity requirements, as described in Section 611.956; and

7)         The supplier must comply with the applicable reporting and recordkeeping requirements, as described in Section 611.957.

BOARD NOTE:  Derived from 40 CFR 141.500 through 141.503.

(Source:  Amended at 44 Ill. Reg. 6996, effective April 17, 2020)