Chapter NR 810

1Based on calculations in sub. (1) or (4), as applicable.

NR 810.34(4) (4) Following completion of the second round of source water monitoring required under s. NR 809.331 (2), water suppliers for filtered systems shall recalculate their Cryptosporidium bin concentration using the Cryptosporidium results reported under s. NR 809.331 (2) and following the procedures in sub. (2) (a) to (d). Systems shall then redetermine their bin classification using this bin concentration and the table in sub. (3).

NR 810.34(5) (5) Water suppliers shall report their bin classification of the water system as follows:

NR 810.34(5)(a) (a) Water suppliers for filtered systems shall report the initial bin classification under par. (c) to the department for approval no later than 6 months after the system is required to complete initial source water monitoring based on the schedule in s. NR 809.331 (3).

NR 810.34(5)(b) (b) Water suppliers for filtered systems shall report the bin classification under sub. (4) to the department for approval no later than 6 months after the system is required to complete the second round of source water monitoring based on the schedule in s. NR 809.331 (3).

NR 810.34(5)(c) (c) The bin classification report to the department shall include a summary of source water monitoring data and the calculation procedure used to determine bin classification.

NR 810.34(6) (6) Failure to comply with the conditions of sub. (5) is a violation of the treatment technique requirement.

NR 810.34 History History: CR 09-073: cr. Register November 2010 No. 659, eff. 12-1-10.

NR 810.35 NR 810.35 Cryptosporidium treatment requirements for filtered systems.

NR 810.35(1) (1) Filtered systems shall provide the level of additional treatment for Cryptosporidium specified in this paragraph based on their bin classification as determined under s. NR 810.34 and according to the schedule in s. NR 810.37.

NR 810.35(2) (2) Systems shall use the following treatment or management practices:

NR 810.35(2)(a) (a) Filtered systems shall use one or more of the treatment and management options listed in s. NR 810.41, termed the microbial toolbox, to comply with the additional Cryptosporidium treatment required in sub. (1).

NR 810.35(2)(b) (b) Filtered systems classified in Bin 3 and Bin 4 shall achieve at least 1-log of the additional Cryptosporidium treatment required under sub. (1) using either one or a combination of the following: bag filters, bank filtration, cartridge filters, chlorine dioxide, membranes, ozone, or UV, as described in ss. NR 810.42 to 810.46.

NR 810.35(3) (3) Failure by a filtered system in any month to achieve treatment credit by meeting criteria in ss. NR 810.41 to 810.46 for microbial toolbox options that is at least equal to the level of treatment required in sub. (1) is a violation of the treatment technique requirement.

NR 810.35(4) (4) If the department determines during a sanitary survey or an equivalent source water assessment that after a filtered system completed the monitoring conducted under s. NR 809.331 (1) or 809.331 (2), significant changes occurred in the system's watershed that could lead to increased contamination of the source water by Cryptosporidium, the system shall take actions specified by the department to address the contamination. These actions may include additional source water monitoring or implementing microbial toolbox options listed in s. NR 810.41, or both. - See PDF for table

NR 810.35 History History: CR 09-073: cr. Register November 2010 No. 659, eff. 12-1-10.

NR 810.36 NR 810.36 Cryptosporidium treatment requirements for groundwater under the direct influence of surface water systems that do not filter. Section NR 811.42 requires filtration for all surface water sources. The following applies only to GWUDI systems not required to filter.

NR 810.36(1) (1) Determination of mean Cryptosporidium level.

NR 810.36(1)(a) (a) Following completion of the initial source water monitoring required under s. NR 809.331 (1), water suppliers for unfiltered systems shall calculate the arithmetic mean of all Cryptosporidium sample concentrations reported under s. NR 809.331 (1). Water suppliers shall report this value to the department for approval no later than 6 months after the month the system is required to complete initial source water monitoring based on the schedule in s. NR 809.331 (3).

NR 810.36(1)(b) (b) Following completion of the second round of source water monitoring required under s. NR 809.331 (2), water suppliers for unfiltered systems shall calculate the arithmetic mean of all Cryptosporidium sample concentrations reported under s. NR 809.331 (2). Water suppliers shall report this value to the department for approval no later than 6 months after the month the system is required to complete the second round of source water monitoring based on the schedule in s. NR 809.331 (3).

NR 810.36(1)(c) (c) If the monthly Cryptosporidium sampling frequency varies, water suppliers shall first calculate a monthly average for each month of monitoring. Systems shall then use these monthly average concentrations, rather than individual sample concentrations, in the calculation of the mean Cryptosporidium level in par. (a) or (b).

NR 810.36(1)(d) (d) The report to the department of the mean Cryptosporidium levels calculated under pars. (a) and (b) shall include a summary of the source water monitoring data used for the calculation.

NR 810.36(1)(e) (e) Failure to comply with the conditions of this subsection is a violation of the treatment technique requirement.

NR 810.36(2) (2) Cryptosporidium inactivation requirements. Unfiltered systems shall provide the level of inactivation for Cryptosporidium specified in this subsection, based on their mean Cryptosporidium levels as determined under sub. (1) and according to the schedule in s. NR 810.37.

NR 810.36(2)(a) (a) Unfiltered systems with a mean Cryptosporidium level of 0.01 oocysts/L or less shall provide at least 2-log Cryptosporidium inactivation.

NR 810.36(2)(b) (b) Unfiltered systems with a mean Cryptosporidium level of greater than 0.01 oocysts/L shall provide at least 3-log Cryptosporidium inactivation.

NR 810.36(3) (3) Inactivation treatment technology requirements. Unfiltered systems shall use chlorine dioxide, ozone, or UV as described in s. NR 810.46 to meet the Cryptosporidium inactivation requirements of this section.

NR 810.36(3)(a) (a) Unfiltered systems that use chlorine dioxide or ozone and fail to achieve the Cryptosporidium inactivation required in sub. (2) on more than one day in the calendar month are in violation of the treatment technique requirement.

NR 810.36(3)(b) (b) Unfiltered systems that use UV light and fail to achieve the Cryptosporidium inactivation required in sub. (2) by meeting the criteria in s. NR 810.46 are in violation of the treatment technique requirement.

NR 810.36(4) (4) Use of two disinfectants. Unfiltered systems shall use a minimum of 2 disinfectants to meet the combined Cryptosporidium inactivation requirements of this section along with the Giardia lamblia and virus inactivation requirements of s. NR 810.31 (1). Each of the 2 disinfectants shall separately achieve the total inactivation required for either Cryptosporidium, Giardia lamblia, or viruses.

NR 810.36 History History: CR 09-073: cr. Register November 2010 No. 659, eff. 12-1-10.

NR 810.37 NR 810.37 Cryptosporidium treatment requirement compliance schedule.

NR 810.37(1) (1) Following initial bin classification under s. NR 810.34 (3), filtered systems shall provide the level of treatment for Cryptosporidium required under s. NR 810.35 according to the schedule in sub. (3).

NR 810.37(2) (2) Following initial determination of the mean Cryptosporidium level under s. NR 810.36 (1) (a), unfiltered systems shall provide the level of treatment for Cryptosporidium required under s. NR 810.36 according to the schedule in sub. (3).

NR 810.37(3) (3) Cryptosporidium treatment compliance dates.

Cryptosporidium Treatment Compliance Dates Table - See PDF for table

1The department may allow up to an additional 2 years for complying with the treatment requirement for systems making capital improvements.

NR 810.37(4) (4) If the bin classification for a filtered system changes following the second round of source water monitoring, as determined under s. NR 810.34, the system shall provide the level of treatment for Cryptosporidium required under s. NR 810.35 on a schedule approved by the department.

NR 810.37(5) (5) If the mean Cryptosporidium level for an unfiltered GWUDI system changes following the second round of monitoring, as determined under s. NR 810.36, and if the system is required to provide a different level of Cryptosporidium treatment under s. NR 810.36 due to this change, the system shall meet this treatment requirement on a schedule approved by the department.

NR 810.37 History History: CR 09-073: cr. Register November 2010 No. 659, eff. 12-1-10.

NR 810.38 NR 810.38 Monitoring requirements.

NR 810.38(1) (1)  Monitoring requirements for groundwater systems under the direct influence of surface water that do not provide filtration. A public water system that uses a groundwater source under the direct influence of surface water and does not provide filtration treatment shall begin monitoring as specified in this subsection on December 31, 1990, or 6 months after the department determines that the groundwater source is under the direct influence of surface water, whichever is later.

NR 810.38(1)(a) (a) Fecal coliform or total coliform density measurements as required by s. NR 810.30 (1) (a) shall be performed on representative source water samples immediately prior to the first or only point of disinfectant application. The water supplier shall sample for fecal or total coliforms at the following minimum frequency each week the system serves water to the public: - See PDF for table

NR 810.38(1)(b) (b) The samples in par. (a) shall be taken on separate days. In addition, one fecal or total coliform density measurement shall be performed every day the system serves water to the public and the turbidity of the source water exceeds one NTU. These samples count toward the weekly coliform sampling requirement.

NR 810.38(1)(c) (c) Turbidity measurements as required by s. NR 810.30 (1) (b) shall be performed on representative grab samples of source water immediately prior to the first or only point of disinfectant application every 4 hours, or more frequently, that the system serves water to the public. A public water system may substitute continuous turbidity monitoring for grab sample monitoring if it validates the continuous measurement for accuracy on a regular basis using a protocol approved by the department.

NR 810.38(1)(d) (d) The total inactivation ratio for each day that the system is in operation shall be determined based on the CT values in ss. NR 810.47 to 810.62, as appropriate. The parameters necessary to determine the total inactivation ratio shall be monitored as follows:

NR 810.38(1)(d)1. 1. Temperature of the disinfected water shall be measured at least once per day at each residual disinfectant concentration sampling point.

NR 810.38(1)(d)2. 2. If the system uses chlorine, the pH of the disinfected water shall be measured at least once per day at each chlorine residual disinfectant concentration sampling point.

NR 810.38(1)(d)3. 3. The disinfectant contact time (“T") shall be determined for each day during peak hourly flow.

NR 810.38(1)(d)4. 4. The residual disinfectant concentration (“C") of the water before or at the first customer shall be measured each day during peak hourly flow.

NR 810.38(1)(d)5. 5. If a system uses a disinfectant other than chlorine, the water supplier may demonstrate to the department, through the use of a department approved protocol for on-site disinfection challenge studies or other information satisfactory to the department, that CT values other than those specified in ss. NR 810.54 to 810.62, and other operational parameters, are adequate to demonstrate that the system is achieving the minimum inactivation rates specified in s. NR 810.31 (1) (a).

NR 810.38(1)(e) (e) For any given disinfectant, the total inactivation ratio shall be calculated as follows:

NR 810.38(1)(e)1. 1. If the system uses only one point of disinfectant application, the water supplier may determine the total inactivation ratio based on either of the following 2 methods:

NR 810.38(1)(e)1.a. a. One inactivation ratio (CTcalc/CT99.9) is determined before or at the first customer during peak hourly flow and if the (CTcalc/CT99.9) is greater than or equal to 1.0, the 99.9% Giardia lamblia inactivation requirement has been achieved.

NR 810.38(1)(e)1.b. b. Successive (CTcalc/CT99.9) values, representing sequential inactivation ratios, are determined between the point of disinfectant application and a point before or at the first customer during peak hourly flow. Under this alternative, the following method shall be used to calculate the total inactivation ratio:

Determine (CTcalc/CT99.9) for each sequence.

Add the (CTcalc/CT99.9) values together S(CTcalc/CT99.9).

If S (CTcalc/CT99.9) > or = 1.0, the 99.9% Giardia lamblia inactivation requirement has been achieved.

NR 810.38(1)(e)2. 2. If the system uses more than one point of disinfectant application before or at the first customer, the water supplier shall determine the CT value of each disinfection sequence immediately prior to the next point of disinfectant application during peak flow. The (CTcalc/CT99.9) value of each sequence and S (CTcalc/CT99.9) shall be calculated using the method in subd. 1. b. to determine if the system is in compliance with s. NR 810.31.

NR 810.38(1)(e)3. 3. Although not required, the total percent inactivation for a system with one or more points of residual disinfectant concentration monitoring may be calculated by solving the following equation:

Percent inactivation = 100 - (100/10), where

z = 3 x summation of (CTcalc/CT99.9)

NR 810.38(1)(f) (f) The residual disinfectant concentration of the water entering the distribution system shall be monitored continuously, and the lowest value shall be recorded each day, except that if there is a failure in the continuous monitoring equipment, grab sampling every 4 hours may be conducted in lieu of continuous monitoring, but for no more than 5 working days following the failure of the equipment, and systems serving 3,300 or fewer persons may take grab samples in lieu of providing continuous monitoring on an ongoing basis at the following prescribed frequencies: - See PDF for table

NR 810.38(1)(g) (g) The day's samples to meet par. (f) cannot be taken at the same time. The sampling intervals are subject to department review and approval. If at any time the residual disinfectant concentration falls below 0.2 mg/l in a system using grab sampling in lieu of continuous monitoring, the water supplier for the system shall take a grab sample every 4 hours until the residual concentration is equal to or greater than 0.2 mg/l.

NR 810.38(1)(h) (h) The residual disinfectant concentration of the water in the distribution system shall be measured as follows:

NR 810.38(1)(h)1. 1. The residual disinfectant concentration shall be measured at least at the same points in the distribution system and at the same time as total coliforms are sampled, except that the department may allow the water supplier for a public water system which uses a groundwater source, to take disinfectant residual samples at points other than the total coliform sampling points if the department determines that the points are more representative of treated (disinfected) water quality within the distribution system. Heterotrophic bacteria, measured as heterotrophic plate count (HPC) as specified in s. NR 809.311 (1), Table F, may be measured in lieu of residual disinfectant concentration, when approved by the department.

NR 810.38(1)(h)2. 2. If the department determines, based on site specific considerations, that a system has no means for having a sample transported and analyzed for HPC by a certified laboratory under the requisite time and temperature conditions specified by s. NR 809.311, Table F, and that the system is providing adequate disinfection in the distribution system, the requirements of subd. 1. do not apply to that system.

NR 810.38(2) (2) Monitoring requirements for systems using filtration treatment. Water suppliers for a public water system that uses a surface water source or a groundwater source under the direct influence of surface water and provides filtration treatment shall monitor in accordance with all of the following:

NR 810.38(2)(a) (a) Turbidity measurements as specified in s. NR 810.29 shall be performed on representative samples of the system's combined filter effluent water every 4 hours, or more frequently, that the system serves water to the public. A water supplier may substitute continuous turbidity monitoring for grab sample monitoring if it validates the continuous measurement for accuracy on a regular basis using a protocol approved by the department. For any systems using slow sand filtration or filtration treatment other than conventional filtration treatment, direct filtration or diatomaceous earth filtration, the department may reduce the sampling frequency to once per day if it determines that less frequent monitoring is sufficient to indicate effective filtration performance. For systems serving 500 or fewer persons, the department may reduce the turbidity sampling frequency to once per day, regardless of the type of filtration treatment used, if the department determines that less frequent monitoring is sufficient to indicate effective filtration performance.

NR 810.38(2)(b) (b) Water suppliers for systems using conventional filtration treatment or direct filtration shall conduct continuous monitoring of turbidity for each individual filter using a method approved in s. NR 809.113 (1), Tables A and B and shall calibrate turbidimeters using the procedure specified by the manufacturer. Water suppliers shall record the results of individual filter monitoring every 15 minutes. If there is a failure in the continuous monitoring equipment, the water supplier shall conduct grab sampling every 4 hours in lieu of continuous monitoring, until the turbidimeter is repaired and back on-line. The water supplier shall repair the equipment no later than 5 working days after the failure or the system is in violation.

NR 810.38(2)(c) (c) The residual disinfectant concentration of the water entering the distribution system shall be monitored continuously, and the lowest value shall be recorded each day, except that if there is a failure in the continuous monitoring equipment, grab sampling every 4 hours may be conducted in lieu of continuous monitoring, but for no more than 5 working days following the failure of the equipment. Water suppliers for systems serving 3,300 or fewer persons may take grab samples in lieu of providing continuous monitoring on an ongoing basis at the frequencies each day prescribed as follows: - See PDF for table

1The day's samples cannot be taken at the same time. The sampling intervals are subject to department review and approval.

If at any time the residual disinfectant concentration falls below 0.2 mg/l in a system using grab sampling in lieu of continuous monitoring, the water supplier shall take a grab sample every 4 hours until the residual disinfectant concentration is equal to or greater than 0.2 mg/l.

NR 810.38(2)(d) (d) The residual disinfectant concentration in the distribution system shall be measured as follows:

NR 810.38(2)(d)1. 1. The residual disinfectant concentration shall be measured at least at the same points in the distribution system and at the same time as total coliforms are sampled. The department may allow a public water system which uses both a surface water source or a groundwater source under direct influence of surface water, and a groundwater source to take disinfectant residual samples at points other than the total coliform sampling points if the department determines that the points are more representative of treated or disinfected water quality within the distribution system. Heterotrophic bacteria, measured as heterotrophic plate count (HPC) as specified in s. NR 809.311 (1), Table F, may be measured in lieu of residual disinfectant concentration, when approved by the department.

NR 810.38(2)(d)2. 2. If the department determines, based on site specific considerations, that a system has no means for having a sample transported and analyzed for HPC by a certified laboratory under the requisite time and temperature conditions specified in s. NR 809.311 (1), Table F, and that the system is providing adequate disinfection in the distribution system, the requirements of subd. 1. do not apply to that system.

NR 810.38 History History: CR 09-073: cr. Register November 2010 No. 659, eff. 12-1-10.

NR 810.39 NR 810.39 Reporting requirements.

NR 810.39(1) (1) Water suppliers shall report sampling schedules under s. NR 809.332 and source water monitoring results under s. NR 809.336 to the department unless they notify the department that they will not conduct source water monitoring due to meeting the criteria of s. NR 809.331 (4).

NR 810.39(2) (2) Water suppliers for filtered systems shall report the Cryptosporidium bin classification of their system to the department as described in s. NR 810.34.

NR 810.39(3) (3) Water suppliers for unfiltered GWUDI systems shall report the mean source water Cryptosporidium level of their system to the department as described in s. NR 810.36.

NR 810.39(4) (4) Water suppliers for filtered and unfiltered systems shall report disinfection profiles and benchmarks to the department as described in s. NR 810.32 prior to making a significant change in disinfection practice.

NR 810.39(5) (5) Water suppliers for filtered and unfiltered systems shall report to the department in accordance with the following table for any microbial toolbox options used to comply with treatment requirements under s. NR 810.35 or 810.36. Alternatively, the department may approve a system to certify operation within required parameters for treatment credit rather than reporting monthly operational data for toolbox options.

Microbial Toolbox Reporting Requirements - See PDF for table

NR 810.39 History History: CR 09-073: cr. Register November 2010 No. 659, eff. 12-1-10.

NR 810.40 NR 810.40 Recordkeeping requirements.

NR 810.40(1) (1) Public water systems shall keep results from the initial round of source water monitoring under s. NR 809.331 (1) and the second round of source water monitoring under s. NR 809.331 (2) until 3 years after bin classification under s. NR 810.34 for filtered systems or determination of the mean Cryptosporidium level under s. NR 810.35 for unfiltered GWUDI systems for the particular round of monitoring.

NR 810.40(2) (2) Public water systems shall keep any notification to the department that the systems will not conduct source water monitoring due to meeting the criteria of s. NR 809.331 (4) for 3 years from the date of notification.

NR 810.40(3) (3) Public water systems shall keep the results of treatment monitoring associated with microbial toolbox options under ss. NR 810.42 to 810.46 for 3 years from the date of monitoring.