Chapter NR 809

NR 809.547(2)(e) (e) The water supplier for a non-transient non-community water system or a community water system that meets the criteria of s. NR 809.546 (2) (g) that does not have enough taps that can supply first-draw samples, may apply to the department in writing to substitute non-first-draw samples. Water suppliers for these public water systems shall collect as many first-draw samples from appropriate taps as possible and identify sampling times and locations that would likely result in the longest standing time for the remaining sites. The department may waive the requirement for prior departmental approval of non-first-draw sample sites selected by the water supplier, either through department rule or written notification to the water supplier.

NR 809.547(3) (3) Number of samples. Water suppliers shall collect at least one sample during each monitoring period specified in sub. (4) from the number of sites listed in the following column titled “standard monitoring.” A water supplier conducting reduced monitoring under sub. (4) (d) may collect one sample from the number of sites specified in the second following column during each monitoring period specified in sub. (4) (d). The department may specify sampling locations when a water supplier is conducting reduced monitoring. Such reduced monitoring sites shall be representative of the sites required for standard monitoring. A water supplier for a public water system that has fewer than five drinking water taps that can be used for human consumption meeting the sample site criteria of sub. (1) of this section to reach the required number of sample sites listed in this subsection, shall collect at least one sample from each tap and then shall collect additional samples from those taps on different days during the monitoring period to meet the required number of sites. Alternatively the department may allow water suppliers of these public water systems to collect a number of samples less than the number of sites specified in this subsection, provided that 100 percent of all taps that can be used for human consumption are sampled. The department may approve this reduction of the minimum number of samples in writing based on a request from the water supplier or onsite verification by the department.

NR 809.547(4) (4) Timing of monitoring.

NR 809.547(4)(a) (a) Initial tap sampling. The first 6-month monitoring period for small, medium and large-size systems shall begin on the following dates:

NR 809.547(4)(a)1. 1. The water suppliers of all large systems shall monitor during 2 consecutive 6-month periods.

NR 809.547(4)(a)2. 2. The water suppliers of all small and medium-size systems shall monitor during each 6-month monitoring period until one of the following occurs:

NR 809.547(4)(a)2.a. a. The public water system exceeds the lead or copper action level and is therefore required to implement the corrosion control treatment requirements under s. NR 809.542, in which case the water supplier shall continue monitoring in accordance with par. (b).

NR 809.547(4)(a)2.b. b. The public water system meets the lead or copper action levels during 2 consecutive 6-month monitoring periods, in which case the water supplier may reduce monitoring in accordance with par. (d).

NR 809.547(4)(b) (b) Monitoring after installation of corrosion control and source water treatment.

NR 809.547(4)(b)1. 1. Any large system with optimal corrosion control treatment installed pursuant to s. NR 809.542 (4) (d) shall be monitored during 2 consecutive 6-month periods by the date specified in s. NR 809.542 (4) (e).

NR 809.547(4)(b)2. 2. Any small or medium-size system with optimal corrosion control treatment installed pursuant to s. NR 809.542 (5) (e) shall be monitored during 2 consecutive 6-month monitoring periods by the date specified in s. NR 809.542 (5) (f).

NR 809.547(4)(b)3. 3. Any water supplier that installs source water treatment pursuant to s. NR 809.544 (1) (c) shall monitor during 2 consecutive 6-month monitoring periods by the date specified in s. NR 809.544 (1) (d).

NR 809.547(4)(c) (c) Monitoring after the department specifies water quality parameter values for optimal corrosion control. After the department approves the values for water quality control parameters under s. NR 809.543 (6), the water supplier shall monitor during each subsequent 6-month monitoring period, with the first monitoring period to begin on the date the department specifies the optimal values under s. NR 809.543 (6).

NR 809.547(4)(d) (d) Reduced monitoring.

NR 809.547(4)(d)1. 1. The water supplier for a small or medium-size water system that meets the lead and copper action levels during each of 2 consecutive 6-month monitoring periods may reduce the number of samples in accordance with sub. (3), and reduce the frequency of sampling to once per year. The water supplier for a small or medium water system collecting fewer than five samples as specified in sub. (3) of this section, that meets the lead and copper action levels during each of two consecutive six-month monitoring periods may reduce the frequency of sampling to once per year. In no case may the water supplier reduce the number of samples required below the minimum of one sample per available tap. The water supplier shall begin this sampling during the calendar year immediately following the end of the second consecutive six-month monitoring period.

NR 809.547(4)(d)2. 2. The water supplier for a public water system that meets the lead action level and maintains the range of values for the water quality control parameters reflecting optimal corrosion control treatment specified by the department under s. NR 809.543 (6) and (7) during each of two consecutive six-month monitoring periods may reduce the frequency of monitoring to once per year and reduce the number of lead and copper samples in accordance with sub. (3) of this section if they receive written approval from the department. This sampling shall begin during the calendar year immediately following the end of the second consecutive six-month monitoring period. The department shall review monitoring, treatment, and other relevant information submitted by the water supplier in accordance with s. NR 809.55, and shall notify the water supplier in writing when it determines the public water system is eligible to commence reduced monitoring pursuant to this paragraph. The department shall review, and where appropriate, revise its determination when the water supplier submits new monitoring or treatment data, or when other data relevant to the number and frequency of tap sampling becomes available.

NR 809.547(4)(d)3. 3. The water supplier for a small or medium-size water system that meets the lead and copper action levels during three consecutive years of monitoring may reduce the frequency of monitoring for lead and copper from annually to once every three years. The water supplier for a public water system that meets the lead action level and maintains the range of values for the water quality control parameters reflecting optimal corrosion control treatment specified by the department under s. NR 809.543 (6) during three consecutive years of monitoring may reduce the frequency of monitoring from annually to once every three years if they receives written approval from the department. Samples collected once every three years shall be collected no later than every third calendar year. The department shall review monitoring, treatment, and other relevant information submitted by the water supplier in accordance with s. NR 809.55, and shall notify the water supplier in writing when it determines the public water system is eligible to reduce the frequency of monitoring to once every three years. The department shall review, and where appropriate, revise its determination when the water supplier submits new monitoring or treatment data, or when other data relevant to the number and frequency of tap sampling becomes available.

NR 809.547(4)(d)4. 4. A water supplier that reduces the number and frequency of sampling shall collect these samples from representative sites included in the pool of targeted sampling sites identified in sub. (1). A water supplier sampling annually or less frequently shall conduct the lead and copper tap sampling during the months of June, July, August or September unless the department has approved a different sampling month.

NR 809.547(4)(d)4.a. a. The department, at its discretion, may approve a different period for conducting the lead and copper tap sampling for water suppliers collecting a reduced number of samples. Such a period shall be no longer than four consecutive months and must represent a time of normal operation where the highest levels of lead are most likely to occur. For a non-transient noncommunity water system that does not operate during the months of June through September, and for which the period of normal operation where the highest levels of lead are most likely to occur is not known, the department shall designate a period that represents a time of normal operation for the public water system. This sampling shall begin during the period approved or designated by the department in the calendar year immediately following the end of the second consecutive six-month monitoring period for water suppliers initiating annual monitoring and during the three-year period following the end of the third consecutive calendar year of annual monitoring for public water systems initiating triennial monitoring.

NR 809.547(4)(d)4.b. b. Water suppliers monitoring annually, that have been collecting samples during the months of June through September and that receive department approval to alter their sample collection period under this subd. 4. a. shall collect their next round of samples during a time period that ends no later than 21 months after the previous round of sampling. Water suppliers monitoring triennially that have been collecting samples during the months of June through September, and receive department approval to alter the sampling collection period as under this subd. 4. a. shall collect their next round of samples during a time period that ends no later than 45 months after the previous round of sampling. Subsequent rounds of sampling shall be collected annually or triennially, as required by this section. Water suppliers for small water systems with waivers, granted pursuant to sub. (7), that have been collecting samples during the months of June through September and receive department approval to alter their sample collection period under this subd. 4. a. shall collect their next round of samples before the end of the 9-year period.

NR 809.547(4)(d)5. 5. Any water supplier that demonstrates for 2 consecutive 6-month monitoring periods that the tap water lead level computed under s. NR 809.54 (3) (c) is less than or equal to 0.005 mg/L and the tap water copper level computed under s. NR 809.54 (3) (c) is less than or equal to 0.65 mg/L may reduce the number of samples in accordance with sub. (3) and reduce the frequency of sampling to once every 3 calendar years.

NR 809.547(4)(d)6. 6.

NR 809.547(4)(d)6.a. a. Water suppliers for public water systems that are on reduced monitoring shall increase monitoring by the following: Water suppliers for a small or medium-sized water system subject to reduced monitoring that exceeds the lead or copper action level shall resume sampling in accordance with par. (c) and collect the number of samples specified for standard monitoring under sub. (3). A water supplier shall also conduct water quality parameter monitoring in accordance with s. NR 809.548 (2), (3) or (4) during the monitoring period in which the action level was exceeded. A water supplier for any public water system subject to reduced monitoring frequency that fails to operate within the range of values for the water quality control parameters specified by the department under s. NR 809.543 (6) shall resume tap water sampling in accordance with par. (c) and collect the number of samples specified for standard monitoring under sub. (3).

NR 809.547(4)(d)6.b. b. A water supplier for any public water system subject to the reduced monitoring frequency that fails to meet the lead action level during any four-month monitoring period or that fails to operate at or above the minimum value or within the range of values for the water quality parameters specified by the department under s. NR 809.543 (6) for more than 9 days in any 6-month period specified in s. NR 809.548 (4) shall conduct tap water sampling for lead and copper at the frequency specified in par. (c), collect the number of samples specified for standard monitoring under sub. (3), and shall resume monitoring for water quality parameters within the distribution system in accordance with s. NR 809.548 (4). This standard tap water sampling shall begin no later than the six-month period beginning January 1 of the calendar year following the lead action level exceedance or water quality parameter excursion.

NR 809.547(4)(d)7. 7. A water supplier for a public water system under subd. 6. b. may resume reduced monitoring for lead and copper at the tap and for water quality parameters within the distribution system under the following conditions:

NR 809.547(4)(d)7.a. a. The water supplier may resume annual monitoring for lead and copper at the tap at the reduced number of sites specified in sub. (3) after they have completed two subsequent six-month rounds of monitoring that meet the criteria of par. (d) 2. and the public water system has received written approval from the department that it is appropriate to resume reduced monitoring on an annual frequency. This sampling shall begin during the calendar year immediately following the end of the second consecutive six-month monitoring period.

NR 809.547(4)(d)7.b. b. The water supplier may resume triennial monitoring for lead and copper at the tap at the reduced number of sites after they demonstrate through subsequent rounds of monitoring that the public water system meets the criteria of either par. (d) 3. or 5. and the water supplier has received written approval from the department that it is appropriate to resume triennial monitoring.

NR 809.547(4)(d)7.c. c. The water supplier may reduce the number of water quality parameter tap water samples required in accordance with s. NR 809.548 (5) (a) and the frequency with which they collect such samples in accordance with s. NR 809.548 (5) (b). The water supplier may not resume triennial monitoring for water quality parameters at the tap until they demonstrate, in accordance with the requirements of s. NR 809.548 (5) (b) that the public water system has re-qualified for triennial monitoring.

NR 809.547(4)(d)8. 8. A water supplier for a public water system subject to a reduced monitoring frequency under par. (d) shall notify the department in writing in accordance with s. NR 809.55 (1) (c) 3. of any upcoming long-term change in treatment or addition of a new source as described in that section. The department must review and approve the addition of a new source or long-term change in water treatment before it is implemented by the water supplier. After approved modifications are completed the water supplier may resume reduced monitoring for lead and copper under the following conditions:

NR 809.547(4)(d)8.a. a. The water supplier may resume annual monitoring for lead and copper at the tap at the reduced number of sites specified in sub. (3) after they have completed 2 subsequent 6-month rounds of monitoring that meet the criteria in subd. 2. and the water supplier has received written approval from the department that it is appropriate to resume reduced monitoring on an annual frequency.

NR 809.547(4)(d)8.b. b. The water supplier may resume triennial monitoring for lead and copper at the tap at the reduced number of sites after they demonstrate through subsequent rounds of monitoring that the public water system meets the criteria of either subd. 3. or 5. and the water supplier has received written approval from the department that it is appropriate to resume triennial monitoring.

NR 809.547(4)(d)8.c. c. The water supplier for a public water system may reduce the number of water quality parameter tap water samples required in accordance with s. NR 809.548 (5) (a) and the frequency with which they collect such samples in accordance with s. NR 809.548 (5) (b). The water supplier may not resume triennial monitoring for water quality parameters at the tap until the public water system demonstrates, in accordance with the requirements of s. NR 809.548 (5) (b), that the public water system has re-qualified for triennial monitoring.

NR 809.547(4)(d)9. 9. The water supplier for a public water system subject to a reduced monitoring frequency under this paragraph that either adds a new source of water or changes any water treatment shall inform the department in writing in accordance with s. NR 809.55 (1) (e). The department may require the water supplier to resume sampling in accordance with sub. (2) (c) and collect the number of samples specified for standard monitoring under sub. (3) or take other appropriate steps such as increased water quality parameter monitoring or re-evaluation of its corrosion control treatment given the potentially different water quality considerations.

NR 809.547(5) (5) Additional monitoring by water suppliers. The results of any monitoring conducted in addition to the minimum requirements of this section shall be considered by the water supplier and the department in making any determinations, i.e., calculating the 90th percentile lead or copper level, under this subchapter.

NR 809.547(6) (6) Invalidation of lead or copper tap water samples. A sample invalidated under this subsection does not count toward determining lead or copper 90th percentile levels under s. NR 809.54 (3) (c) or toward meeting the minimum monitoring requirements of sub. (3).

NR 809.547(6)(a) (a) The department may invalidate a lead or copper tap water sample if at least one of the following conditions is met:

NR 809.547(6)(a)1. 1. The laboratory establishes that improper sample analysis caused erroneous results.

NR 809.547(6)(a)2. 2. The department determines that the sample was taken from a site that did not meet the site selection criteria of this section.

NR 809.547(6)(a)3. 3. The sample container was damaged in transit.

NR 809.547(6)(a)4. 4. There is substantial reason to believe that the sample was subject to tampering.

NR 809.547(6)(b) (b) The water supplier shall report the results of all samples to the department and all supporting documentation for samples the water supplier believes should be invalidated.

NR 809.547(6)(c) (c) To invalidate a sample under par. (a), the decision and the rationale for the decision shall be documented in writing. The department may not invalidate a sample solely on the grounds that a follow-up sample result is higher or lower than that of the original sample.

NR 809.547(6)(d) (d) The water supplier shall collect replacement samples for any samples invalidated under this subsection if, after the invalidation of one or more samples, the public water system has too few samples to meet the minimum requirements of sub. (3). Any replacement samples shall be taken as soon as possible, but no later than 20 days after the date the department invalidates the sample or by the end of the applicable monitoring period, whichever occurs later. Replacement samples taken after the end of the applicable monitoring period may not also be used to meet the monitoring requirements of a subsequent monitoring period. The replacement samples shall be taken at the same locations as the invalidated samples or, if that is not possible, at locations other than those already used for sampling during the monitoring period.

NR 809.547(7) (7) Monitoring waivers for small water systems. The water supplier of any small water system that meets the criteria of this subsection may apply to the department to reduce the frequency of monitoring for lead and copper under this section to once every 9 years, also known as a “full waiver,” if the public water system meets all of the materials criteria specified in par. (a) and all of the monitoring criteria specified in par. (b). If department rules permit, the water supplier for any small water system that meets the criteria in pars. (a) and (b) only for lead, or only for copper, may apply to the department for a waiver to reduce the frequency of tap water monitoring to once every 9 years for that contaminant only, also known as a “partial waiver.”

NR 809.547(7)(a) (a) Materials criteria. The water supplier shall demonstrate that the distribution system of their public water supply system and service lines and all drinking water supply plumbing, including plumbing conveying drinking water within all residences and buildings connected to the public water system, are free of lead-containing materials or copper-containing materials, as those terms are defined in this paragraph, as follows:

NR 809.547(7)(a)1. 1. ‘Lead waiver.’ To qualify for a full waiver, or a waiver of the tap water monitoring requirements for lead, known as a “lead waiver,” the water supplier shall provide certification and supporting documentation to the department that the public water system is free of all lead-containing materials, and complies with all of the following:

NR 809.547(7)(a)1.a. a. The public water system contains no plastic pipes which contain lead plasticizers, or plastic service lines which contain lead plasticizers.

NR 809.547(7)(a)1.b. b. The public water system is free of lead service lines, lead pipes, lead soldered pipe joints, and leaded brass or bronze alloy fittings and fixtures, unless the fittings and fixtures meet the specifications of any standard established pursuant to 42 USC 300g-6(e).

NR 809.547 Note Note: 42 USC 300g-6(e) is section 1417 (e) of the federal Safe Drinking Water Act.

NR 809.547(7)(a)2. 2. ‘Copper waiver.’ To qualify for a full waiver, or a waiver of the tap water monitoring requirements for copper, hereafter known as a “copper waiver,” the water supplier shall provide certification and supporting documentation to the department that the public water system contains no copper pipes or copper service lines.

NR 809.547(7)(b) (b) Monitoring criteria for waiver issuance. The water supplier for the public water system shall have completed at least one 6-month round of standard tap water monitoring for lead and copper at sites approved by the department and from the number of sites required by sub. (3) and demonstrate that the 90th percentile levels for any and all rounds of monitoring conducted since the public water system became free of all lead-containing and copper-containing materials, as appropriate, meet the following criteria:

NR 809.547(7)(b)1. 1. ‘Lead waiver.’ To qualify for a lead waiver, the water supplier shall demonstrate that the 90th percentile lead level does not exceed 0.005 mg/L.

NR 809.547(7)(b)2. 2. ‘Copper waiver.’ To qualify for a copper waiver, the water supplier shall demonstrate that the 90th percentile copper level does not exceed 0.65 mg/L.

NR 809.547(7)(c) (c) Department approval of waiver application. The department shall notify the water supplier of its waiver determination, in writing, setting forth the basis of its decision and any condition of the waiver. As a condition of the waiver, the department may require the water supplier to perform specific activities, such as limited monitoring, periodic outreach to customers to remind them to avoid installation of materials that might void the waiver, to avoid the risk of lead or copper concentration of concern in tap water. The water supplier for the small water system shall continue monitoring for lead and copper at the tap as required by sub. (4) (a) to (d), as appropriate, until water supplier receives written notification from the department that the waiver has been approved.

NR 809.547(7)(d) (d) Monitoring frequency for public water systems with waivers.

NR 809.547(7)(d)1. 1. A water supplier with a full waiver shall conduct tap water monitoring for lead and copper in accordance with sub. (4) (d) 4. at the reduced number of sampling sites identified in sub. (3) at least once every 9 years and provide the materials certification specified in par. (a) for both lead and copper to the department along with the monitoring results.

NR 809.547(7)(d)2. 2. A water supplier with a partial waiver shall conduct tap water monitoring for the waived contaminant in accordance with sub. (4) (d) 4. at the reduced number of sampling sites specified in sub. (3) at least once every 9 years and provide the materials certification specified in par. (a) pertaining to the waived contaminant along with the monitoring results. The water supplier shall also continue to monitor for the non-waived contaminant in accordance with requirements of sub. (4) (a) to (d), as appropriate.

NR 809.547(7)(d)3. 3. Any water supplier for a public water system with a full or partial waiver shall notify the department in writing in accordance with s. NR 809.55 (1) (c) 3. of any upcoming long-term change in treatment or addition of a new source, as described in that section. The department must review and approve the addition of a new source or long-term change in water treatment before it is implemented by the public water system. The department has the authority to require the public water system to add or modify waiver conditions. The department may require recertification that the public water system is free of lead-containing or copper-containing materials, or both, and may require additional rounds of monitoring, if it deems the modifications are necessary to address treatment or source water changes at the public water system.

NR 809.547(7)(d)4. 4. If a water supplier for a public water system with a full or partial waiver becomes aware that the public water system is no longer free of lead-containing or copper-containing materials as a result of new construction or repairs, the water supplier shall notify the department in writing no later than 60 days after becoming aware of a change.

NR 809.547(7)(e) (e) Continued eligibility. If the public water system continues to satisfy the requirements of par. (d), the waiver shall be renewed automatically, unless any of the conditions listed in subds. 1. to 3. occurs. A water supplier for a public water system whose waiver has been revoked may re-apply for a waiver at the time the public water system again meets the appropriate materials and monitoring criteria of pars. (a) and (b).

NR 809.547(7)(e)1. 1. A public water system with a lead waiver no longer satisfies the materials criteria of par. (a) 1. if the 90th percentile lead level is greater than 0.005 mg/L.

NR 809.547(7)(e)2. 2. A public water system with a copper waiver no longer satisfies the materials criteria of par. (a) 2. if the 90th percentile copper level is greater than 0.65 mg/L.

NR 809.547(7)(e)3. 3. The department notifies the water supplier, in writing, that the waiver has been revoked, setting forth the basis of its decision.

NR 809.547(7)(f) (f) Requirements following waiver revocation. A public water system whose full or partial waiver has been revoked by the department is subject to the corrosion control treatment and lead and copper tap water monitoring requirements, as follows:

NR 809.547(7)(f)1. 1. If the public water system exceeds the lead or copper action level, or both, the water supplier shall implement corrosion control treatment in accordance with the deadlines specified in s. NR 809.542 (5), and any other applicable requirements of this paragraph.

NR 809.547(7)(f)2. 2. If the public water system meets both the lead and the copper action level, the water supplier shall monitor for lead and copper at the tap no less frequently than once every 3 years using the reduced number of sample sites specified in sub. (3).

NR 809.547(7)(g) (g) Pre-existing waivers. Small water system waivers approved by the department in writing prior to April 11, 2000 shall remain in effect under the following conditions:

NR 809.547(7)(g)1. 1. If the water supplier for a public water system has demonstrated that the public water system is free of both lead-containing and copper-containing materials, as required by par. (a) and that its 90th percentile lead levels and 90th percentile copper levels meet the criteria of par. (b), the waiver remains in effect so long as the public water system continues to meet the waiver eligibility criteria of par. (e). The first round of tap water monitoring conducted pursuant to par. (d) shall be completed no later than 9 years after the last time the water supplier has monitored for lead and copper at the tap. Samples collected every nine years shall be collected no later than every ninth calendar year.

NR 809.547(7)(g)2. 2. If the public water system has met the materials criteria of par. (a) but has not met the monitoring criteria of par. (b), the water supplier shall conduct a round of monitoring for lead and copper at the tap demonstrating that the public water system meets the criteria of par. (b) to meet initial monitoring requirements. Thereafter, the waiver shall remain in effect as long as the public water system meets the continued eligibility criteria of par. (e). The first round of tap water monitoring conducted pursuant to par. (d) shall be completed no later than 9 years after the round of monitoring conducted pursuant to par. (b).

NR 809.547 History History: CR 09-073: cr. Register November 2010 No. 659, eff. 12-1-10; corrections in (4) (d) 5. and (6) (intro.) made under s. 13.92 (4) (b) 7., Stats., Register November 2010 No. 659; CR 15-049: am. (3), (4) (d) 2. Register March 2016 No. 723, eff. 4-1-16.

NR 809.548 NR 809.548 Monitoring requirements for water quality parameters. Water suppliers for all large systems, and for all small and medium-size systems that exceed the lead or copper action level, shall monitor water quality parameters in addition to lead and copper in accordance with this section. The requirements of this section are summarized in the table at the end of this section.

NR 809.548(1) (1) General requirements.

NR 809.548(1)(a) (a) Sample collection methods.

NR 809.548(1)(a)1. 1. Tap samples shall be representative of water quality throughout the distribution system taking into account the number of persons served, the different sources of water, the different treatment methods employed by the water supplier, and seasonal variability. Tap sampling under this section is not required to be conducted at taps targeted for lead and copper sampling under s. NR 809.547 (1).

NR 809.548(1)(a)2. 2. Samples collected at the entry points to the distribution system shall be from locations representative of each source after treatment. If a public water system draws water from more than one source and the sources are combined before distribution, the water supplier shall sample at an entry point to the distribution system during periods of normal operating conditions, i.e., when water is representative of all sources being used.

NR 809.548(1)(b) (b) Number of samples.

NR 809.548(1)(b)1. 1. The water supplier shall collect 2 tap samples for applicable water quality parameters during each monitoring period specified under subs. (2) to (5) from the following number of sites:

NR 809.548(1)(b)2. 2. Except as provided in sub. (3) (c), water suppliers shall collect 2 samples for each applicable water quality parameter at each entry point to the distribution system during each monitoring period specified in sub. (2).

NR 809.548(2) (2) Initial sampling. Water suppliers of all large water systems shall measure the applicable water quality parameters as specified below at taps and at each entry point to the distribution system during each 6-month monitoring period specified in s. NR 809.547 (4) (a). Water suppliers of all small and medium-size systems shall measure the applicable water quality parameters at the locations specified below during each 6-month monitoring period specified in s. NR 809.547 (4) (a) during which the public water system exceeds the lead or copper action level.

NR 809.548(2)(a) (a) At taps:

NR 809.548(2)(a)1. 1. pH;

NR 809.548(2)(a)2. 2. Alkalinity;

NR 809.548(2)(a)3. 3. Orthophosphate, when an inhibitor containing a phosphate compound is used;

NR 809.548(2)(a)4. 4. Silica, when an inhibitor containing a silicate compound is used;

NR 809.548(2)(a)5. 5. Calcium;

NR 809.548(2)(a)6. 6. Conductivity; and

NR 809.548(2)(a)7. 7. Water temperature.

NR 809.548(2)(b) (b) At each entry point to the distribution system: all of the applicable parameters listed in par. (a).

NR 809.548(3) (3) Monitoring after installation of corrosion control. The water supplier of any large system which installs optimal corrosion control treatment pursuant to s. NR 809.542 (4) (d) shall measure the water quality parameters at the following locations and frequencies during each 6-month monitoring period specified in s. NR 809.547 (4) (b) 1. The water supplier of any small or medium-size system which installs optimal corrosion control treatment shall conduct such monitoring during each 6-month monitoring period specified in s. NR 809.547 (4) (b) 2. in which the public water system exceeds the lead or copper action level.