Section NR 811.43 - Treatment of water from groundwater sources Treatment of water from groundwater sources shall meet the following requirements:
(1) DISINFECTION CAPABILITY REQUIRED. All municipal water systems constructed or modified after December 1, 2010, shall have equipment and the necessary appurtenances that can continuously disinfect the water. The department may require the installation of disinfection equipment at existing other-than-municipal water systems if necessary to ensure a safe water supply.(2) DISINFECTANT RESIDUAL REQUIREMENTS. Disinfection of water drawn from groundwater sources is to supplement and not replace proper well location, construction, and source protection. When disinfection of water drawn from a groundwater source is required to maintain bacteriologically safe water, the residual maintained in the distribution system and the residual monitoring is the same as that required for surface water in s. NR 811.42 (5).(3) DISINFECTION REQUIREMENTS FOR WELLS. Specific disinfection requirements for wells are provided in subch. II. Any additional disinfection requirements for wells will be developed by the department if necessary on a case by case basis.(4) DISINFECTION OF GROUNDWATER EXPOSED TO THE ATMOSPHERE AS PART OF A TREATMENT PROCESS. Disinfection of water drawn from groundwater sources is required at facilities that expose the water to the atmosphere, such as open basins, open filters, air stripping towers, or gravity aerators.(5) REQUIRED ACTIONS FOR WELLS WITH NON-COMPLYING WATER QUALITY. One of the following actions shall be taken after consulting with the department if untreated water drawn from a groundwater source exceeds one or more of the primary maximum contaminant levels in ch. NR 809 or a department health advisory: (a) The well shall be removed from service and permanently abandoned.(b) The well shall be removed from service and either reconstructed or provided with permanent treatment to provide complying water quality. Wells may temporarily continue in service without reconstruction or providing permanent treatment only as approved by the department. Department approval is required prior to reconstructing the well or providing water treatment. Under emergency conditions, the department may allow temporary use of a well from which bacteriologically contaminated groundwater is drawn if disinfection adequate to ensure safe water is provided. In such cases, disinfection measures meeting the requirements of sub. (3) shall be provided. A continuous boil water notice may be required by the department during all or part of this interim period if deemed necessary by the department to protect public health.(6) GROUNDWATER UNDER THE DIRECT INFLUENCE OF SURFACE WATER. The department may allow the use of water drawn from a groundwater source that has been determined by the department to be under the direct influence of surface water provided that treatment facilities meeting the requirements of subch. II of ch. NR 810 are provided as approved by the department. The total plant removal and inactivation shall provide a minimum 3-log inactivation of Cryptosporidium and Giardia Lamblia plus 4-log inactivation of viruses. The disinfectant residual maintained in the distribution system and residual monitoring shall be the same as required for treatment of water drawn from a surface water source in s. NR 811.42 (5). The department may approve modified treatment requirements for other-than-municipal public water systems if surface water treatment is impractical and if sufficient treatment can be provided. The supplier of water shall contact the department to determine what modified treatment will be approved.(7) REDUNDANCY. All critical treatment components shall be provided with redundancy.(8) CT VALUES. CT values for the inactivation of Giardia Lamblia, Cryptosporidium, and viruses can be found in ss. NR 810.47 to 810.62.(9) TREATMENT FOR NITRATE. If the source water quality exceeds the nitrate maximum contaminant level set under s. NR 809.11 and treatment, blending, or other department-approved methods are provided to reduce the entry point nitrate concentration beneath the maximum contaminant level, a continuous nitrate analyzer shall be provided at the entry point. The continuous nitrate analyzer shall be programmed to include shut off controls or alarms if the nitrate concentration at the entry point exceeds the maximum contaminant level.Wis. Admin. Code Department of Natural Resources NR 811.43
CR 09-073: cr. Register November 2010 No. 659, eff. 12-1-10.Amended by, CR 22-074: am. (1), (4), cr. (9) Register January 2024 No. 817, eff. 2/1/2024