NR 809.31(1)(dr)2.
2. Seasonal systems shall be monitored every month that they are in operation unless they meet the criteria in subd.
2. a. to
c. to be eligible for monitoring less frequently than monthly beginning April 1, 2016, except as provided under par.
(ar).
NR 809.31(1)(dr)2.a.
a. Seasonal systems that are monitored less frequently than monthly shall have an approved sample siting plan that designates the time period for monitoring based on site-specific considerations (e.g., during periods of highest demand or highest vulnerability to contamination). Water suppliers of seasonal systems shall collect compliance samples during this time period.
NR 809.31(1)(dr)3.
3. The department may exempt any seasonal system from some or all of the requirements for seasonal systems if the entire distribution system remains pressurized during the entire period that the seasonal system is not operating, except that seasonal systems that are monitored less frequently than monthly shall be monitored during the vulnerable period as designated by the department.
NR 809.31(1)(e)
(e)
Sample collection time intervals. Water suppliers for public water systems shall collect samples at regular time intervals throughout the month, except that for public water systems which use only groundwater and serve 4,900 persons or fewer, may collect all required samples on a single day if the samples are taken from different sites.
NR 809.31(1)(eg)
(eg)
Minimum required number of samples after MCL violation or treatment technique trigger. Water suppliers shall take at least the minimum number of required samples even if the public water system has had an
E. coli MCL violation or has exceeded the coliform treatment technique triggers in s.
NR 809.313.
NR 809.31(1)(er)
(er)
Sampling in excess of requirements. Water suppliers may conduct more compliance monitoring than is required by this section to investigate potential problems in the distribution system and use monitoring as a tool to assist in uncovering problems. Water suppliers may take more than the minimum number of required routine samples and shall include the results in calculating whether the coliform treatment technique trigger in s.
NR 809.313 has been exceeded only if the samples are taken in accordance with the existing sample siting plan and are representative of water throughout the distribution system.
NR 809.31(1)(f)
(f)
Special purpose samples. Special purpose samples such as those taken to determine whether disinfection practices are sufficient following pipe placement, replacement or repair, may not be used to determine whether the coliform treatment technique trigger has been exceeded. Repeat samples taken pursuant to sub.
(2) are not considered special purpose samples, and shall be used to determine whether the coliform treatment technique trigger has been exceeded.
NR 809.31(1)(g)
(g)
Analyses required after turbidity exceedances at selected systems. A water supplier for a public water system that uses surface water or groundwater under the direct influence of surface water as defined in s.
NR 809.04 (40), and does not provide filtration in compliance with s.
NR 810.29, shall collect at least one sample in the distribution system near the first service connection each day one or more turbidity measurements of the source water obtained as specified in s.
NR 810.38 (1) (c), exceeds 1 NTU. This sample shall be analyzed for the presence of total coliforms. The water supplier shall collect this coliform sample within 24 hours of the first exceedance unless the department determines that the water supplier, for logistical reasons beyond their control, cannot have the sample analyzed within 30 hours of collection. Results from this coliform monitoring shall be used to determine whether the coliform treatment technique trigger has been exceeded in s.
NR 809.313.
NR 809.31(2)(a)(a) If a routine sample is total coliform-positive, the water supplier for a public water system shall collect a set of repeat samples within 24 hours of being notified of the positive result. The water supplier shall collect no fewer than 3 repeat samples for each total coliform-positive sample found. The department may extend the 24-hour limit on a case-by-case basis if the water supplier has a logistical problem that is beyond its control in collecting the repeat samples within 24 hours. In the case of an extension, the department shall specify how much time the water supplier has to collect repeat samples. The department may not waive the requirement for a water supplier to collect repeat samples in this paragraph or pars.
(b) to
(c).
NR 809.31(2)(b)
(b) Unless the provisions of subds.
1. and
2. are met, the water supplier shall collect at least one repeat sample from the sampling tap where the original total coliform-positive sample was taken, and at least one repeat sample at a tap within 5 service connections upstream and at least one repeat sample at a tap within five service connections downstream of the original sampling site. If a total coliform-positive sample is at the end of the distribution system, or one service connection away from the end of the distribution system, the water supplier shall take all required repeat samples. However, the department may allow an alternative sampling location in lieu of the requirement to collect at least one repeat sample upstream or downstream of the original sampling site. Except as provided in subd.
2., public water systems required to conduct triggered source water monitoring under s.
NR 809.325 shall take ground water source samples in addition to repeat samples required under this paragraph.
NR 809.31(2)(b)1.
1. A water supplier may propose repeat monitoring locations to the department that the water supplier believes to be representative of a pathway for contamination of the distribution system. A water supplier may elect to specify either alternative fixed locations or criteria for selecting repeat sampling sites on a situational basis in a standard operating procedure (SOP) in its sample siting plan. The water supplier shall design its SOP to focus the repeat samples at locations that best verify and determine the extent of potential contamination of the distribution system area based on specific situations. The department may modify the SOP or require alternative monitoring locations as needed.
NR 809.31(2)(b)2.
2. A water supplier of a ground water system serving 1,000 or fewer people may propose repeat sampling locations to the department that differentiate potential source water and distribution system contamination (e.g., by sampling at entry points to the distribution system). A water supplier of a ground water system with a single well required to conduct triggered source water monitoring may, with written department approval, take one of the repeat samples at the monitoring location required for triggered source water monitoring under s.
NR 809.325 if the water supplier demonstrates to the department's satisfaction that the sample siting plan remains representative of water quality in the distribution system. If approved by the department, the water supplier may use that dual purpose sample result to meet the monitoring requirements in both s.
NR 809.325 and this section.
NR 809.31(2)(b)2.a.
a. If a dual purpose repeat sample taken at the monitoring location required for triggered source water monitoring is
E. coli-positive, the public water system has violated the
E. coli MCL and shall also comply with s.
NR 809.325 (2) (e). If a water supplier takes more than one repeat sample at the monitoring location required for triggered source water monitoring, the water supplier may reduce the number of additional source water samples required under s.
NR 809.325 (2) (e) by the number of repeat samples taken at that location that were not
E. coli-positive.
NR 809.31(2)(b)2.b.
b. If a water supplier takes more than one repeat sample at the monitoring location required for triggered source water monitoring under s.
NR 809.325 (2). and more than one repeat sample is
E. coli-positive, the public water system has violated the
E. coli MCL and shall comply with s.
NR 809.327.
NR 809.31(2)(b)2.c.
c. If all repeat samples taken at the monitoring location required for triggered source water monitoring are
E. coli-negative and a repeat sample taken at a monitoring location other than the one required for triggered source water monitoring is
E. coli-positive, the public water system has violated the
E. coli MCL, but is not required to comply with s.
NR 809.325 (2) (e).
NR 809.31(2)(b)3.
3. The department may review, revise, and approve, as appropriate, repeat sampling proposed by water suppliers under subds.
1. and
2. The water supplier shall demonstrate that the sample siting plan remains representative of the water quality in the distribution system. The department may determine that monitoring at the entry point to the distribution system, especially at ground water systems without disinfection is effective to differentiate between potential source water and distribution system problems.
NR 809.31(2)(c)
(c) Water suppliers at ground water systems may use a repeat sample, taken at the source or all of the sources serving the location of each routine positive sample, to meet the requirements of both this paragraph and s.
NR 809.325 (2) (d). In cases where more than one source serves the location of the routine positive sample or samples, repeat samples shall be taken from each of the sources to satisfy the requirements of this paragraph and s.
NR 809.325 (2) (d).
NR 809.31(2)(d)
(d) The water supplier shall collect all repeat samples on the same day, except that the department may allow a water supplier for a public water system with a single service connection to collect the required set of repeat samples over a 3-day period or to collect a larger volume repeat sample in one or more sample containers of any size, as long as the total volume collected is at least 300 mL.
NR 809.31(2)(e)
(e) If one or more repeat samples in the set is total coliform-positive, the water supplier shall collect an additional set of repeat samples in the manner specified in pars.
(a) to
(d). The additional set of samples shall be collected within 24 hours after the water supplier is notified of the positive result, unless the department extends the limit as provided in par.
(a). The water supplier shall repeat this process until either total coliforms are not detected in one complete set of repeat samples or the water supplier determines that the coliform treatment technique trigger specified in s.
NR 809.313 has been exceeded and the water supplier notifies the department as specified in s.
NR 809.80 (2). If a trigger identified in s.
NR 809.313 is exceeded as a result of a routine sample being total coliform-positive, water suppliers are required to conduct only one round of repeat monitoring for each total coliform-positive routine sample.
NR 809.31(2)(f)
(f) Water suppliers collecting samples on a quarterly or annual frequency shall conduct additional routine monitoring the month following one or more total coliform-positive samples regardless of whether the positive samples resulted in a Level 1 treatment technique trigger. Water suppliers shall collect at least three routine samples during the next month, after consultation with the department, except that the department may waive this requirement if the conditions of subd.
1.,
2., or
3. are met. Water suppliers may either collect samples at regular time intervals throughout the month or may collect all required routine samples on a single day if samples are taken from different sites. Water suppliers shall use the results of additional routine samples in coliform treatment technique trigger calculations under s.
NR 809.313 (1).
NR 809.31(2)(f)1.
1. The department may waive the requirement to collect 3 routine samples during the next month the public water system provides water to the public if the department performs a site visit before the end of the next month the public water system provides water to the public. Although a sanitary survey need not be performed, the site visit shall be sufficiently detailed to allow the department to determine whether additional monitoring or any corrective action is needed. The department may not approve an employee of the public water system to perform this site visit, even if the employee is an agent approved by the department to perform sanitary surveys.
NR 809.31(2)(f)2.
2. The department may waive the requirement to collect 3 routine samples during the next month the public water system provides water to the public if the department has determined why the sample was total coliform positive and establishes that the water supplier has corrected the problem or will correct the problem before the end of the next month the public water system serves water to the public. In this case, the decision to waive the following month's additional monitoring requirement will be documented in writing, signed by a qualified department official, and made available to the public. The written documentation shall describe the specific cause of the total coliform positive sample and what action the water supplier has taken or will take to correct this problem.
NR 809.31(2)(f)3.
3. The requirement to collect 3 routine samples during the next month the public water system provides water to the public shall not be waived solely on the grounds that all repeat samples are total coliform-negative. The water supplier shall collect at least one routine sample before the end of the next month the public water system serves water to the public and use it to determine compliance with the treatment technique trigger for total coliforms in s.
NR 809.31, unless the department has determined that the water supplier corrected the contamination problem before the water supplier collected the set of repeat samples required in pars.
(a) to
(e) and all repeat samples were total coliform negative.
NR 809.31(2)(g)
(g) After a water supplier collects a routine sample and before learning the results of the analysis of that sample, if the water supplier collects another routine sample from within 5 adjacent service connections of the initial sample, and the initial sample after analysis is found to contain total coliforms, then the water supplier may count the subsequent sample as a repeat sample instead of as a routine sample.
NR 809.31(2)(h)
(h) Results of all routine and repeat samples not invalidated by the department shall be included in determining whether any coliform treatment technique triggers specified in s.
NR 809.313 have been exceeded. If any trigger has been exceeded, water suppliers shall complete assessments as required in s.
NR 809.313.
NR 809.31(2m)(a)(a)
Increased monitoring requirements for public water systems on quarterly or annual monitoring. Except as specified in pars.
(d) and
(e), water suppliers at public water systems on quarterly or annual monitoring that experience any of the events identified in subds.
1. to
4. shall begin monthly monitoring the month following the event. A water supplier at a public water system on annual monitoring that experiences the event identified in subd.
5. shall begin quarterly monitoring the quarter following the event. The water supplier shall continue monthly or quarterly monitoring until the requirements in par.
(b) for quarterly monitoring or par.
(c) for annual monitoring are met. A public water system on monthly monitoring for reasons other than those identified in subds.
1. to
4. is not considered to be on increased monitoring for the purposes of pars.
(b) and
(c).
NR 809.31(2m)(a)1.
1. The public water system triggers a Level 2 assessment or two Level 1 assessments under the provisions of s.
NR 809.313 in a rolling 12-month period.
NR 809.31(2m)(a)3.
3. The public water system has a coliform treatment technique violation.
NR 809.31(2m)(a)4.
4. The public water system has two coliform monitoring violations in a rolling 12-month period, or is a non-community public water system and has one coliform monitoring violation and one Level 1 assessment under the provisions of s.
NR 809.313 in a rolling 12-month period for a public water system on quarterly monitoring.
NR 809.31(2m)(a)5.
5. The public water system has one coliform monitoring violation for a public water system on annual monitoring. For transient non-community public water systems, the department may elect to not count monitoring violations under sub.
(9) if the missed sample is collected no later than the end of the monitoring period following the monitoring period in which the sample was missed. The water supplier shall collect the make-up sample in a different week than the routine sample for that monitoring period and shall collect the sample as soon as possible during the monitoring period, except that this is not allowed under par.
(c). This authority does not affect the provisions of sub.
(9) and s.
NR 809.312 (2).
NR 809.31(2m)(b)
(b)
Requirements for public water systems on increased monitoring to return to quarterly monitoring. The department may reduce the monitoring frequency for a public water system on monthly monitoring triggered under par.
(a) to quarterly monitoring if the public water system meets the criteria in subds.
1. and
2. NR 809.31(2m)(b)1.
1. Within the last 12 months, the public water system shall have a completed sanitary survey or a site visit by the department or a voluntary Level 2 assessment by a party approved by the department, be free of sanitary defects, and have a protected water source.
NR 809.31(2m)(b)2.
2. The public water system shall have a clean compliance history for a minimum of 12 months. For transient non-community public water systems, the department may elect to not count monitoring violations, as allowed under sub.
(9), if the missed sample is collected no later than the end of the monitoring period following the monitoring period in which the sample was missed. The water supplier shall collect the make-up sample in a different week than the routine sample for that monitoring period and should collect the sample as soon as possible during the monitoring period, except that this is not allowed under par.
(c). This authority does not affect the provisions of sub.
(9) and s.
NR 809.312 (2).
NR 809.31(2m)(c)
(c)
Requirements for systems on increased monitoring to qualify for annual monitoring. The department may reduce the monitoring frequency for a transient non-community public water system on increased monitoring under par.
(a) if the transient non-community public water system meets the criteria in par.
(d) and the criteria in subds.
1. and
2. NR 809.31(2m)(c)1.
1. The department shall conduct an annual site visit and the water supplier shall correct all identified sanitary defects. The water supplier may substitute a voluntary Level 2 assessment conducted by a party approved by the department in place of the department's annual site visit in any given year.
NR 809.31(2m)(c)2.
2. The water supplier shall have in place or adopt one or more additional enhancements to the water system barriers to contamination in subds.
2. a. to
2. e. NR 809.31(2m)(c)2.c.
c. Continuous disinfection entering the distribution system and a residual in the distribution system in accordance with criteria specified by the department.
NR 809.31(2m)(c)2.e.
e. Other equivalent enhancements to public water system barriers to contamination as approved by the department.
NR 809.31(2m)(d)
(d)
Allowance for transient non-community water systems to monitor annually. The department may allow water suppliers at transient non-community water systems to monitor annually for total coliform and
E. coli following conditions that would require increased monitoring under par.
(a), provided the water supplier meets the requirements of subd.
1. or
2. NR 809.31(2m)(d)1.
1. For water systems that began operation and conducted coliform monitoring prior to April 1, 2016, the water supplier shall have done all of the following:
NR 809.31(2m)(d)1.a.
a. Completed all required total coliform monitoring in the previous calendar year.
NR 809.31(2m)(d)1.c.
c. Corrected all significant deficiencies or is following a department agreed upon schedule for correcting all significant deficiencies.
NR 809.31(2m)(d)1.d.
d. Received a level 2 assessment within 30 days of any level 1 assessment trigger identified after April 1, 2016, and corrected all sanitary defects or is following a department agreed upon schedule for correcting all sanitary defects.
NR 809.31(2m)(d)1.e.
e. Completed all repeat sampling requirements associated with any total coliform positive identified after April 1, 2016.
NR 809.31(2m)(d)2.
2. For public water systems that began operation or began coliform monitoring on or after April 1, 2016, the water supplier shall meet all of the requirements of subd. 1 and shall have completed at least one year of coliform monitoring at a frequency of no less than quarterly.
NR 809.31(2m)(e)
(e)
Allowance for non-transient non-community water systems to monitor quarterly. The department may allow a water supplier of a non-transient non-community water system to monitor quarterly for total coliform and
E. coli following conditions that would require increased monitoring under par.
(a), provided the water supplier meets the same requirements specified for transient non-community water systems in par.
(d) 1. a. to
f. NR 809.31(3)(a)
(a) A total coliform-positive sample invalidated under this subsection does not count towards meeting the minimum monitoring requirements of this section.
NR 809.31(3)(b)
(b) The department may invalidate a total coliform-positive sample only if the conditions of subd.
1.,
2. or
3. are met.
NR 809.31(3)(b)1.
1. A certified laboratory establishes that improper sample analysis caused the total coliform-positive result.
NR 809.31(3)(b)2.
2. The department, on the basis of the results of repeat samples collected as required by sub.
(2) (a) to
(e), determines that the total coliform-positive sample resulted from a domestic or other non-distribution system plumbing problem. A sample may not be invalidated by the department on the basis of repeat sample results alone, unless all repeat samples collected at the same tap as the original total coliform-positive sample are also total coliform-positive, and all repeat samples collected at a location other than the original tap are total coliform-negative. The department will not invalidate a total coliform-positive sample on the basis of repeat samples if all the repeat samples are total coliform-negative, or if the public water system has only one service connection.
NR 809.31(3)(b)3.
3. The department has substantial grounds to believe that a total coliform-positive result is due to a circumstance or condition which does not reflect water quality in the distribution system. In this case, the water supplier shall still collect all repeat samples required, and shall use them to determine whether a coliform treatment technique trigger in s.
NR 809.313 has been exceeded. To invalidate a total coliform-positive sample under this paragraph, the decision with the rationale for the decision shall be documented in writing, approved by a qualified department official and available to the public for inspection. The document shall state the specific cause of the total coliform-positive sample, and what action the water supplier has taken or will take, to correct this problem. The department may not invalidate a total coliform-positive sample solely on the grounds that all repeat samples are total coliform-negative.
NR 809.31(3)(c)
(c) A laboratory shall invalidate a total coliform sample if the sample produces a turbid culture in the absence of gas production using an analytical method where gas formation is examined for, example, the Multiple Tube Fermentation Technique, produces a turbid culture in the absence of an acid reaction in the Presence-Absence Coliform Test, or exhibits confluent growth or produces colonies too numerous to count with an analytical method using a membrane filter, for example, Membrane Filter Technique, except that a laboratory shall not invalidate a total coliform sample if total coliforms are detected. If a laboratory invalidates a sample because of such interference, the water supplier shall collect another sample from the same location as the original sample within 24 hours of being notified of the interference problem, and have it analyzed for the presence of total coliforms. The water supplier shall continue to re-sample every 24 hours and have the samples analyzed until a valid result is obtained. The department may waive the 24 hour time limit on a case-by-case basis. Alternatively, the department may implement criteria for waiving the 24-hour sampling time limit to use in lieu of case-by-case extensions.
NR 809.31(4)(a)
(a) If any routine or repeat sample is total coliform-positive, the water supplier shall analyze that total coliform-positive culture medium to determine if
E. coli are present. If
E. coli are present, the water supplier shall notify the department by the end of the day when the water supplier is notified of the test result, unless the water supplier is notified of the result after normal department business hours, in which case the water supplier shall notify the department before the end of the next business day.
NR 809.31(4)(b)
(b) The department may allow a water supplier for a public water system, on a case-by-case basis, to forgo
E. coli testing on a total coliform-positive sample if that water supplier assumes that the total coliform-positive sample is
E. coli positive. Accordingly, the water supplier shall notify the department as specified in par.
(a) and the provisions of s.
NR 809.30 (2) apply.
NR 809.31(5)
(5)
Groundwater system raw water sampling. In addition to sampling from the distribution system, each water supplier for a public water system providing disinfection shall obtain at least one sample every 3 months from each well prior to the point of treatment. For public water systems which have more than one well in the same location and utilizing the same aquifer, the supplier of water may sample only one of the wells each time on an alternating basis. If a well has a high potential for contamination, the department may, in individual cases, require more frequent sampling.
NR 809.31(6)
(6)
Surface water system raw water sampling. At surface water facilities, the microbiological quality of the source water shall be monitored sufficiently to maintain quality control of the treatment process. Water suppliers shall establish a schedule for each plant, subject to review and modification by the department.
NR 809.31 Note
Note: Generally, enumeration methods such as membrane filter, numeric enzyme substrate, or 5 tube fermentation tests and heterotrophic plate counts of the raw, settled and finished water on an established schedule will be necessary to meet this requirement.
NR 809.31(7)
(7)
Heterotrophic plate counts. At all waterworks which have a potential for high total bacteria levels because of the water quality, the method of treatment, chemical addition or other cause, the department may require heterotrophic plate counts pursuant to an established schedule. Analyses shall be conducted in accordance with the analytical requirements in s.
NR 809.311 (1), Table F.
NR 809.31(9)(a)(a) Failure to take every required routine or additional routine sample in a compliance period is a monitoring violation.
NR 809.31(9)(b)
(b) Failure to analyze for
E. coli following a total coliform-positive routine sample is a monitoring violation.
NR 809.31(10)(a)(a) Failure to submit a monitoring report or completed assessment form after a water supplier properly conducts monitoring or assessment in a timely manner is a reporting violation.
NR 809.31(10)(b)
(b) Failure to notify the department following an
E. coli-positive sample as required by sub.
(4) in a timely manner is a reporting violation.
NR 809.31(10)(c)
(c) Failure to submit certification of completion of department-approved start-up procedure by a seasonal system is a reporting violation.
NR 809.31 History
History: CR 09-073: cr.
Register November 2010 No. 659, eff. 12-1-10;
CR 15-049: am. (1) (title), (a), cr. (1) (ag), (ar), renum. (1) (b) 1. to (b) and am., r. (1) (b) 2., renum. (1) (c) to (d) 4. and am., renum. (1) (d) to (c) and am., cr. (1) (de), (dg), (dr), am. (1) (e), cr. (1) (eg), (er), am. (1) (f), (g), (2) (a), renum. (2) (b) to (b) (intro.) and am., cr. (2) (b) 1. to 3., am. (2) (c) to (e), r. and recr. (2) (f) (intro.), am. (2) (f) 1., 2., cr. (2) (f) 3., am. (2) (h), cr. (2m), am. (3) (b) 2., 3., (c), (4) to (6), cr. (9), (10)
Register March 2016 No. 723, eff. 4-1-16; corrections in (1) (d) 2. (intro.), (2) (a) (intro.), (b) (intro.), (f) (intro.), (2m) (d) (intro.), (e), (3) (b) 2. made under s.
35.17, Stats.,
Register March 2016 No. 723; correction in (1) (ag), (ar) made under s.
13.92 (4) (b) 7., Stats.,
Register July 2022 No. 799.
NR 809.311
NR 809.311 Analytical requirements for microbiological contaminants. NR 809.311(1)(1)
Analytical methods. Analyses conducted to determine compliance with s.
NR 809.31 shall be made in accordance with methods listed in Table F.
NR 809.311(2)
(2)
Sample volume. The standard sample volume required for total coliform analysis, regardless of analytical method used, is 100 ml.
NR 809.311(3)
(3)
Sample collection preservation and holding time. NR 809.311(3)(a)
(a) Sample collection for microbiological contaminants under s.
NR 809.30 shall be conducted using the sample preservation, containers and maximum holding time procedures specified in par.
(b).
NR 809.311(3)(b)
(b) Sample preservation requirements and holding times for microbiological samples
are specified in subds.
1. and
2. In all cases, samples shall be analyzed as soon after collection as possible.
NR 809.311(3)(b)1.
1. Total Coliform and
E. coli samples are not required to be preserved by cooling to 10
° C, however it is encouraged during transit. Sodium thiosulfate shall be added to the sample container prior to adding water containing chlorine and the holding time shall be 30 hours.
NR 809.311(3)(b)2.
2. Heterotrophs may be either held at room temperature with a holding time of 6 hours or preserved by cooling to 4
° C with a holding time of 24 hours.
NR 809.311(4)
(4)
Laboratory certification. Analyses under this section shall only be conducted by laboratories that have received certification under ch.
ATCP 77 or approval by EPA.
NR 809.311(5)
(5)
Presence or absence. Water suppliers need only determine the presence or absence of total coliforms; a determination of total coliform density is not required.
NR 809.311 Note
Note: The coliform density may, however, be helpful in selecting a remedial option.
