Chapter NR 810

NR 810.32(2)(f)2. 2. The disinfection benchmark is the lowest monthly mean value, for water systems with one year of profiling data, or the mean of lowest monthly mean values, for water systems with more than one year of profiling data, of the monthly logs of Giardia lamblia and virus log inactivation in each year of profiling data.

NR 810.32 History History: CR 09-073: cr. Register November 2010 No. 659, eff. 12-1-10.

NR 810.33 NR 810.33 Enhanced treatment requirements for Cryptosporidium.

NR 810.33(1) (1) Applicability. The requirements of this section apply to all public water systems supplied by a surface water source and public water systems supplied by a groundwater source under the direct influence of surface water.

NR 810.33(1)(a) (a) Wholesale systems shall comply with the requirements of this section based on the population of the largest system in the combined distribution system.

NR 810.33(1)(b) (b) The requirements of this section for filtered systems apply to water systems required by s. NR 810.29 to provide filtration treatment, whether or not the system is currently operating a filtration system.

NR 810.33(1)(c) (c) The requirements of this section for unfiltered groundwater systems under the direct influence of surface water apply only to unfiltered systems that timely met and continue to meet the filtration avoidance criteria in s. NR 810.30.

NR 810.33(2) (2) Requirements. Public water systems shall comply with the following requirements:

NR 810.33(2)(a) (a) Water suppliers shall conduct an initial and a second round of source water monitoring for each plant that treats a surface water or GWUDI source. This monitoring may include sampling for Cryptosporidium, E. coli, and turbidity as described in s. NR 809.331, to determine what level, if any, of additional Cryptosporidium treatment they shall provide.

NR 810.33(2)(b) (b) Water suppliers for systems that plan to make a significant change to their disinfection practice shall develop disinfection profiles and calculate disinfection benchmarks, as described in s. NR 810.32.

NR 810.33(2)(c) (c) Water suppliers for filtered systems shall determine their Cryptosporidium treatment bin classification as described in s. NR 810.34 and provide additional treatment for Cryptosporidium, if required, as described in s. NR 810.35. All unfiltered GWUDI systems shall provide treatment for Cryptosporidium as described in s. NR 810.36. Filtered systems and unfiltered GWUDI systems shall implement Cryptosporidium treatment according to the schedule in s. NR 810.37.

NR 810.33(2)(d) (d) Water systems with uncovered finished water storage facilities shall comply with the requirements to cover the facility as described in s. NR 810.28. Finished water is that water which has received all required treatment.

NR 810.33(2)(e) (e) Water systems required to provide additional treatment for Cryptosporidium shall implement microbial toolbox options that are designed and operated as described in ss. NR 810.41 to 810.46.

NR 810.33(2)(f) (f) Water suppliers for water systems shall comply with the applicable recordkeeping and reporting requirements described in ss. NR 810.39 and 810.40.

NR 810.33 History History: CR 09-073: cr. Register November 2010 No. 659, eff. 12-1-10.

NR 810.34 NR 810.34 Cryptosporidium bin classification for filtered systems.

NR 810.34(1) (1) Following completion of the initial round of source water monitoring required under s. NR 809.331 (1), water suppliers for filtered systems shall calculate an initial Cryptosporidium bin concentration for each plant for which monitoring was required. Calculation of the bin concentration shall use the Cryptosporidium results reported under s. NR 809.331 (1) and shall follow the procedures in sub. (2) (a) to (e).

NR 810.34(2) (2) 

NR 810.34(2)(a) (a) For filtered systems that collect a total of at least 48 samples, the bin concentration is equal to the arithmetic mean of all sample concentrations.

NR 810.34(2)(b) (b) For filtered systems that collect a total of at least 24 samples, but not more than 47 samples, the bin concentration is equal to the highest arithmetic mean of all sample concentrations in any 12 consecutive months during which Cryptosporidium samples were collected.

NR 810.34(2)(c) (c) For filtered systems that serve fewer than 10,000 people and monitor for Cryptosporidium for only one year, collecting 24 samples in 12 months, the bin concentration is equal to the arithmetic mean of all sample concentrations.

NR 810.34(2)(d) (d) For filtered systems with plants operating only part of the year that monitor fewer than 12 months per year under s. NR 809.331 (5), the bin concentration is equal to the highest arithmetic mean of all sample concentrations during any year of Cryptosporidium monitoring.

NR 810.34(2)(e) (e) 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 applicable calculation for bin classification in pars. (a) to (d).

NR 810.34(3) (3) Water suppliers for filtered systems shall determine their initial bin classification from the following table and using the Cryptosporidium bin concentration calculated under subs. (1) and (2):

Bin Classification Table for Filtered Systems

- See PDF for table

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 ∑(CTcalc/CT99.9).

If ∑ (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 ∑ (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: