Section 327IAC8-2-8.5. Requirement for filtration and disinfection

  5. (a) Effective June 29, 1993, a public water system that uses a surface water source must provide filtration in accordance with this section.

  (b) A public water system that uses a ground water source under the direct influence of surface water shall provide filtration in accordance with this section beginning eighteen (18) months after the commissioner determines that it is under the direct influence of surface water from the date specified in section 8.2 of this rule.

  (c) A public water system that uses a surface water source or a ground water source under the direct influence of surface water must provide treatment consisting of both disinfection, as specified in section 8.6 of this rule, and filtration treatment. Filtration treatment shall be done by one (1) of the following techniques, and the turbidity level of representative samples of a system’s filtered water, regardless of filtration technique used, shall at no time exceed five (5) nephelometric turbidity units (NTU) in any given sample, measured as specified in section 8.7 of this rule:

(1) For systems using conventional filtration or direct filtration, the turbidity level of representative samples of a system’s filtered water must be less than or equal to one-half (0.5) NTU in at least ninety-five percent (95%) of the total number of measurements taken each month, measured as specified in sections 8.7(4) and 8.8(b) of this rule, except that if the commissioner determines that the system is capable of achieving at least ninety-nine and nine-tenths percent (99.9%) removal or inactivation, or both, of Giardia lamblia cysts at some turbidity level higher than one-half (0.5) NTU in at least ninety-five percent (95%) of the total number of measurements taken each month, the commissioner may substitute this higher turbidity limit for that system. However, in no case may the commissioner approve a turbidity limit that allows more than one (1) NTU in more than five percent (5%) of the samples taken each month, measured as specified in sections 8.7(4) and 8.8(b) of this rule. Upon the effective date of this rule, systems serving a population of:

(A) at least ten thousand (10,000) individuals; and

(B) beginning January 1, 2005, fewer than ten thousand (10,000) individuals;

shall meet the turbidity requirements in 327 IAC 8-2.6-3.

(2) For systems using slow sand filtration, the turbidity level of representative samples of a system’s filtered water must be less than or equal to one (1) NTU in at least ninety-five percent (95%) of the measurements taken each month, measured as specified in sections 8.7(4) and 8.8(b) of this rule, except where the commissioner determines that there is no significant interference with disinfection at a higher turbidity level.

(3) For systems using diatomaceous earth filtration, the turbidity level of representative samples of a public water system’s filtered water must be less than or equal to one (1) NTU in at least ninety-five percent (95%) of the measurements taken each month, measured as specified in sections 8.7(4) and 8.8(b) of this rule.

(4) A public water system may use a filtration technology not listed in this subsection if it demonstrates to the commissioner, using pilot plant studies or other means, that the alternative filtration technology, in combination with disinfection treatment that meets section 8.6 of this rule, consistently achieves ninety-nine and nine-tenths percent (99.9%) removal or inactivation, or both, of Giardia lamblia cysts and ninety-nine and ninety-nine hundredths percent (99.99%) removal or inactivation, or both, of viruses. For a system that makes this demonstration, this subsection applies. Upon the effective date of this rule, systems serving a population of:

(A) at least ten thousand (10,000) individuals; and

(B) beginning January 1, 2005, fewer than ten thousand (10,000) individuals;

shall meet the requirements for other filtration technologies in 327 IAC 8-2.6-3.

  (d) During plant operation, each public water system subject to this section shall be operated only by personnel who have been certified by the commissioner under 327 IAC 8-11 through 327 IAC 8-12.

  (e) In addition to complying with requirements in this section, systems serving a population of:

(1) at least ten thousand (10,000) individuals; and

(2) beginning January 1, 2005, fewer than ten thousand (10,000) individuals;

shall also comply with the requirements in 327 IAC 8-2.6. (Water Pollution Control Division; 327 IAC 8-2-8.5; filed Dec 28, 1990, 5:10 p.m.: 14 IR 1024; errata filed Apr 5, 1991, 3:30 p.m.: 14 IR 1626; errata, 14 IR 1730; filed Apr 12, 1993, 11:00 a.m.: 16 IR 2160; filed May 1, 2003, 12:00 p.m.: 26 IR 2816; filed Jun 13, 2005, 2:30 p.m.: 28 IR 3206)