Section NR 810.27 - General requirements for all surface water and groundwater under the direct influence of surface water systems(1) This subchapter establishes criteria under which filtration is required as a treatment technique for public water systems supplied by a surface water source or a groundwater source under the direct influence of surface water. Direct influence shall be determined for individual sources by the department. The department determination of direct influence may be based on site-specific measurements of water quality characteristics such as those stated in s. NR 810.02(25) or documentation of well construction characteristics and geology with field evaluation. These regulations also establish requirements for treatment techniques in lieu of maximum contaminant levels for Giardia lamblia, viruses, heterotrophic plate count bacteria, Legionella, Cryptosporidium and turbidity. Treatment technique requirements apply to every public water system which utilizes surface water or groundwater under the direct influence of surface water and the requirements consist of installing and properly operating water treatment processes which reliably achieve: (a) At least 99.9% or 3-log removal or inactivation of Giardia lamblia cysts 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.(b) At least 99.99% or 4-log removal or inactivation of viruses 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.(c) At least 99.9% or 3-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 system for unfiltered GWUDI systems.(2) A public water system using a surface water source is considered to be in compliance with the requirements of sub. (1) if it meets the filtration requirements in s. NR 810.29 and the disinfection requirements in s. NR 810.31. (3) A public water system using groundwater under the direct influence of surface water is considered to be in compliance with the requirements or sub. (1) if it meets the criteria for avoiding filtration in s. NR 810.30 along with the disinfection requirements in s. NR 810.31; or if it meets the filtration requirements in s. NR 810.29 and it meets the disinfection requirements in s. NR 810.31. (4) Each public water system using a surface water source or a groundwater under the direct influence of surface water shall be operated by qualified personnel who meet the requirements specified by the department.Wis. Admin. Code Department of Natural Resources § NR 810.27
CR 09-073: cr. Register November 2010 No. 659, eff. 12-1-10.