Chapter NR 810

NR 810.31(2)(c)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 may not exceed 5% in one month, for any 2 consecutive months.

V = c + d + e/a + b x 100

where:

a = number of instances where the residual disinfectant concentration is measured.

b = number of instances where the residual disinfectant concentration is not measured but heterotrophic bacteria plate count (HPC) is measured.

c = number of instances where the residual disinfectant concentration is measured but not detected and no HPC is measured.

d = number of instances where no residual disinfectant concentration is detected and where the HPC is > 500/ml.

e = number of instances where the residual disinfectant concentration is not measured and HPC is > 500/ml.

NR 810.31(2)(c)2. 2. If the department determines, based on site specific considerations, that a public water system has no means for having a sample transported and analyzed for HPC by a certified laboratory under the requisite time and temperature conditions required 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.

NR 810.31 History History: CR 09-073: cr. Register November 2010 No. 659, eff. 12-1-10.

NR 810.32 NR 810.32 Disinfection profiling and benchmarking.

NR 810.32(1) (1) Requirements when making a significant change in disinfection practice.

NR 810.32(1)(a) (a) Following the completion of initial source water monitoring under s. NR 809.331, the water supplier for a public water system that plans to make a significant change to its disinfection practice, as defined in par. (b), shall develop disinfection profiles and calculate disinfection benchmarks for Giardia lamblia and viruses as described in sub. (2). Prior to changing the disinfection practice, the water supplier shall notify the department and shall include in this notice all of the following information:

NR 810.32(1)(a)1. 1. A completed disinfection profile and disinfection benchmark for Giardia lamblia and viruses as described in sub. (2).

NR 810.32(1)(a)2. 2. A description of the proposed change in disinfection practice.

NR 810.32(1)(a)3. 3. An analysis of how the proposed change will affect the current level of disinfection.

NR 810.32(1)(b) (b) Significant changes to disinfection practice are defined as any of the following:

NR 810.32(1)(b)1. 1. Changes to the point of disinfection.

NR 810.32(1)(b)2. 2. Changes to the disinfectants used in the treatment plant.

NR 810.32(1)(b)3. 3. Changes to the disinfection process.

NR 810.32(1)(b)4. 4. Any other modification identified by the department as a significant change to disinfection practice. Additional barriers with no change to existing disinfection practices may be exempt from these requirements.

NR 810.32(2) (2) Developing the disinfection profile and benchmark. Water suppliers for public water systems required to develop disinfection profiles under sub. (1) shall follow the requirements of this subsection:

NR 810.32(2)(a) (a) Water suppliers shall monitor at least weekly for a period of 12 consecutive months to determine the total logs of inactivation for Giardia lamblia and viruses. If water suppliers monitor more frequently, the monitoring frequency shall be evenly spaced. Systems that operate for fewer than 12 months per year shall be monitored weekly during the period of operation. Water suppliers shall determine log inactivation for Giardia lamblia through the entire plant, based on the CT99.9 (3 log) values in ss. NR 810.47 to 810.62. Water suppliers shall determine log inactivation for viruses through the entire treatment plant based on a protocol approved by the department.

NR 810.32(2)(b) (b) Water suppliers for systems with a single point of disinfectant application prior to entrance to the distribution system shall conduct the monitoring in subds. 1. to 4. Water suppliers for systems with more than one point of disinfectant application shall conduct the monitoring in subds. 1. to 4. for each disinfection segment. Water suppliers shall monitor the parameters necessary to determine the total inactivation ratio, using analytical methods in s. NR 809.563 (2), Table R.

NR 810.32(2)(b)1. 1. For systems using a disinfectant other than UV, the temperature of the disinfected water shall be measured at each residual disinfectant concentration sampling point during peak hourly flow.

NR 810.32(2)(b)2. 2. For systems using chlorine, the pH of the disinfected water shall be measured at each chlorine residual disinfectant concentration sampling point during peak hourly flow.

NR 810.32(2)(b)3. 3. The disinfectant contact times (“T”) shall be determined during peak hourly flow.

NR 810.32(2)(b)4. 4. The residual disinfectant concentrations (“C”) of the water before or at the first customer and prior to each additional point of disinfection shall be measured during peak hourly flow.

NR 810.32(2)(c) (c) In lieu of conducting new monitoring under par. (b), public water systems may elect to meet the following requirements:

NR 810.32(2)(c)1. 1. Water suppliers for systems that have at least one year of existing data that are substantially equivalent to data collected under par. (b) may use these data to develop disinfection profiles as specified in this section if the water system has neither made a significant change to its treatment practice nor changed sources since the data were collected. Water suppliers may develop disinfection profiles using up to 3 years of existing data.

NR 810.32(2)(c)2. 2. Water suppliers may use disinfection profile or profiles developed previously in lieu of developing a new profile if the water system has not made a significant change, as determined under sub. (1) (b), to its treatment practice or has not changed sources since the profile was developed. Water suppliers for systems that have not developed a virus profile shall develop a virus profile using the same monitoring data on which the Giardia lamblia profile is based.

NR 810.32(2)(d) (d) The water supplier shall calculate the total inactivation ratio for Giardia lamblia as follows:

NR 810.32(2)(d)1. 1. For water systems using only one point of disinfectant application, the water supplier may determine the total inactivation ratio for the disinfection segment based on either of the following methods:

NR 810.32(2)(d)1.a. a. Determine one inactivation ratio (CTcalc/CT99.9) before or at the first customer during peak hourly flow.

NR 810.32(2)(d)1.b. b. Determine successive (CTcalc/CT99.9) values, representing sequential inactivation ratios, between the point of disinfectant application and a point before or at the first customer during peak hourly flow. Under this alternative, the water supplier shall calculate the total inactivation ratio by determining (CTcalc/CT99.9) for each sequence and then adding the (CTcalc/CT99.9) values together to determine (∑ (CTcalc/CT99.9)).

NR 810.32(2)(d)2. 2. For systems using more than one point of disinfectant application before the first customer the water supplier shall determine the CT value of each disinfection segment immediately prior to the next point of disinfectant application, or for the final segment, before or at the first customer, during peak hourly flow. The (CTcalc/CT99.9) value of each segment and (∑ (CTcalc/CT99.9)) shall be calculated using the method in subd. 1.

NR 810.32(2)(d)3. 3. The water supplier shall determine the total logs of inactivation by multiplying the value calculated in subd. 1. or 2. by 3.0.

NR 810.32(2)(e) (e) Water suppliers shall determine the total logs of inactivation for viruses using a protocol approved by the department.

NR 810.32(2)(f) (f) For water systems required to calculate a disinfection benchmark water suppliers shall use the following procedure:

NR 810.32(2)(f)1. 1. For each year of profiling data collected and calculated under this subsection, the water supplier shall determine the lowest mean monthly level of both Giardia lamblia and virus inactivation. The water supplier shall determine the mean Giardia lamblia and virus inactivation for each calendar month for each year of profiling data by dividing the sum of daily or weekly Giardia lamblia and virus log inactivation by the number of values calculated for that month.

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

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.

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.