NR 810.30(2)(c)8.8. A review of the adequacy of the watershed control program to limit potential contamination by Cryptosporidium including: comprehensiveness of the watershed review, the effectiveness of the system’s program to monitor and control detrimental activities occurring in the watershed, and the extent to which the water system has maximized land ownership or controlled land use, or both, within the watershed.

NR 810.30(2)(d)(d) The public water system may not have been identified as a source of a waterborne disease outbreak, or if it has been so identified, the system shall be modified sufficiently to prevent another occurrence, as determined by the department.

NR 810.30(2)(e)(e) The public water system shall comply with the maximum contaminant level (MCL) for total coliforms in s. NR 809.30 at least 11 months of the previous 12 months that the system served water to the public, on an ongoing basis, unless the department determines that failure to meet this requirement was not caused by a deficiency in treatment of the source water.

NR 810.30(2)(f)(f) The public water system shall comply with the requirements for total trihalomethanes, five haloacetic acids, bromate, chlorite, chlorine, chloramines and chlorine dioxide in s. NR 809.561.

NR 810.30(3)(a)(a) A public water system that fails to meet any one of the criteria in subs. (1) and (2), and for which the department has determined in writing that filtration is required, is in violation of a treatment technique requirement.

NR 810.30(3)(b)(b) A public water system that has not installed filtration is in violation of a treatment technique if either of the following apply:

NR 810.30(3)(b)1.1. The turbidity level in a representative sample of the source water immediately prior to the first or only point of disinfection application exceeds 5 NTU.

NR 810.30(4)(4) Additional circumstances when filtration would be required. The department may require a public water system to install filtration even when the system meets the requirements of subs. (1) and (2) if other water quality characteristics or site specific conditions present a threat to public health which could not be eliminated by disinfection alone.

NR 810.31NR 810.31 Disinfection requirements for Giardia lamblia and viruses. A public water system that uses groundwater under the direct influence of surface water and does not provide filtration shall provide disinfection treatment specified in sub. (1) within 18 months after the department determines that the groundwater source is under the influence of surface water. A system that filters and uses surface water or groundwater under the direct influence of surface water as a source shall provide the disinfection treatment specified in sub. (2) when filtration is installed. Failure to meet any requirement of this section is a treatment technique violation.

NR 810.31(1)(1) Disinfection requirements for public water systems using groundwater under the direct influence of surface water that do not provide filtration.

NR 810.31(1)(a)(a) The disinfection treatment shall be sufficient to ensure at least 99.9% (3 log) inactivation of Giardia lamblia cysts and 99.99% (4 log) inactivation of viruses, every day the system serves water to the public. Each day a system serves water to the public, the water supplier shall calculate the CT value from the system’s treatment parameters using the procedure specified in s. NR 810.38 (1) (d), and determine whether this value is sufficient to achieve the specified inactivation rates for Giardia lamblia cysts and viruses. Water suppliers for systems using a disinfectant other than chlorine shall demonstrate to the department through on-site challenge studies or other information that the system is achieving required minimum inactivation rates.

NR 810.31(1)(b)(b) The disinfection system shall have either redundant components, including an auxiliary power supply with automatic start-up and alarm to ensure that disinfectant application is maintained continuously while water is being delivered to the distribution system, or automatic shut-off of water delivery to the distribution system whenever there is less than 0.2 mg/l of residual disinfectant concentration in the water. If the department determines that automatic shut-off of delivery of water to the distribution system would cause an unreasonable risk to health or property, the disinfection system shall have redundant components.

NR 810.31(1)(c)(c) The residual disinfectant concentration in the water entering the distribution system, measured as specified in s. NR 809.563 (2), Table R, may not be less than 0.2 mg/l for more than 4 hours.

NR 810.31(1)(d)1.1. The residual disinfectant concentration in the distribution system, measured as total chlorine, combined chlorine, or chlorine dioxide, as specified in s. NR 809.563 (2), Table R, may not be undetectable in more than 5% of the samples each month, for any 2 consecutive months that the system serves water to the public. Water in the distribution system with a heterotrophic bacteria concentration less than or equal to 500/ml, measured as heterotrophic plate count (HPC) as specified in s. NR 809.311 (1), Table F, is deemed to have a detectable disinfectant residual for purposes of determining compliance with this requirement. Thus, the value “V” in the following formula cannot exceed 5% in one month for any 2 consecutive months.