Wisconsin Administrative Code › Department of Natural Resources › NR 800 - Environmental Protection - Water Supply › Chapter NR 809 - Safe Drinking Water › Subchapter I - Maximum Contaminant Levels, Monitoring and Analytical Requirements for Primary Drinking Water Contaminants › Section NR 809.31 - Distribution system microbiological contaminant monitoring requirements

Current through June 24, 2024
(1)
				  ROUTINE AND REDUCED MONITORING.
(a)
Monitoring site plans.
Water suppliers for all public water
				  systems shall collect total coliform samples at sites which are representative
				  of water throughout the distribution system according to a written sample
				  siting plan. These plans are subject to department review and revision.
				  Monitoring required by this section and s. NR 809.32 may take place at a
				  customer's premise, dedicated sampling station, or other designated compliance
				  sampling location. Routine and repeat sample sites and any sampling points
				  necessary to meet the requirements of s. NR 809.325 shall be identified in the
				  sampling plan.
(ag)
Action
				  after total coliform positive sample.
Following any total
				  coliform-positive sample taken under the provisions of this section, water
				  suppliers shall comply with the repeat monitoring requirements and
E.
				  coli
analytical requirements in subs. (2) and (4).
(ar)
Transition from total coliform
				  rule to revised total coliform rule.
1. Water suppliers of public water systems,
				  including seasonal systems, shall continue to monitor according to the total
				  coliform monitoring schedules that were in effect on March 31, 2016, unless any
				  of the conditions for increased monitoring in sub. (2m) are triggered on or
				  after April 1, 2016, or unless otherwise directed by the department.
2. Beginning April 1, 2016, the department
				  shall perform a special monitoring evaluation during each sanitary survey to
				  review the status of each public water system, including the distribution
				  system, to determine whether the public water system is on an appropriate
				  monitoring schedule. After the department has performed the special monitoring
				  evaluation during each sanitary survey, the department may modify the public
				  water system's monitoring schedule, as necessary, or it may allow the public
				  water system to stay on its existing monitoring schedule, consistent with the
				  provisions of this section. The department may not allow public water systems
				  to begin less frequent monitoring under the special monitoring evaluation
				  unless the public water system has already met the applicable criteria for less
				  frequent monitoring in this section. For seasonal systems on quarterly or
				  annual monitoring, this evaluation shall include review of the approved sample
				  siting plan, which shall designate the time period(s) for monitoring based on
				  site-specific considerations (e.g., during periods of highest demand or highest
				  vulnerability to contamination). The water supplier of the seasonal system
				  shall collect compliance samples during these time periods.
(b)
Monitoring frequency
				  at community water systems.
Water suppliers for community water
				  systems shall take water samples for coliform determination at regular
				  intervals, and in a number proportionate to the population served by the
				  community water system. Water suppliers required to collect multiple samples
				  each month shall sample at geographically representative locations and on dates
				  evenly spaced during the month. The minimum sampling frequency shall be as set
				  forth in the following table:
Population served:
Minimum number of samples per
								  month
25 to 1,000 (Not serving a municipality)
1
25 to 1,000 (Serving a municipality)
2
1,001 to 2,500
2
2,501 to 3,300
3
3,301 to 4,100
4
4,101 to 4,900
5
4,901 to 5,800
6
5,801 to 6,700
7
6,701 to 7,600
8
7,601 to 8,500
9
8,501 to 12,900
10
12,901 to 17,200
15
17,201 to 21,500
20
21,501 to 25,000
25
25,001 to 33,000
30
33,001 to 41,000
40
41,001 to 50,000
50
50,001 to 59,000
60
59,001 to 70,000
70
70,001 to 83,000
80
83,001 to 96,000
90
96,001 to 130,000
100
130,001 to 220,000
120
220,001 to 320,000
150
320,001 to 450,000
180
450,001 to 600,000
210
600,001 to 780,000
240
780,001 to 970,000
270
970,001 to 1,230,000
300
1,230,001 to 1,520,000
330
1,520,001 to 1,850,000
360
1,850,001 to 2,270,000
390
2,270,001 to 3,020,000
420
3,020,001 to 3,960,000
450
3,960,001 or more
480
(c)
Monitoring frequency for coliforms at non-community water
				  systems.
The monitoring frequency for total coliforms for
				  non-community water systems, notwithstanding pars. (dg) and (dr), is as
				  follows:
1. A water supplier for a
				  non-community water system using only groundwater and serving 1,000 persons per
				  day or fewer shall monitor each calendar quarter that the non-community water
				  system provides water to the public.
2. A water supplier for a non-community water
				  system using only groundwater and serving on average more than 1,000 persons
				  per day for any month shall monitor at the same frequency as a like-sized
				  community water system, as specified in par. (b), except that the department
				  may reduce the monitoring frequency, in writing, for any month the average
				  daily population served is 1,000 persons or fewer per day.
3. A water supplier for a non-community water
				  system using surface water, or groundwater under the direct influence of
				  surface water as defined in s. NR 809.04 (40), in total or in part, shall
				  monitor at the same frequency as a like-sized municipal community water system,
				  as specified in par. (b). GWUDI public water systems shall begin monitoring at
				  this frequency beginning 6 months after the department determines that the
				  groundwater source is under the direct influence of surface water.
4. The water supplier for a transient
				  non-community water system serving a school shall sample for coliform bacteria
				  in each calendar quarter during which the public water system provides water to
				  the public, unless the department, on the basis of sub. (2m), determines that
				  more frequent monitoring is appropriate. Transient non-community systems
				  serving schools are not eligible for reduced monitoring under par. (dg) of this
				  section.
(de)
Annual site visits.
Beginning no later than calendar year
				  2017, transient non-community systems on annual monitoring, including seasonal
				  systems, shall have an initial and recurring annual site visit by the
				  department that is equivalent to a Level 2 assessment or an annual voluntary
				  Level 2 assessment that meets the criteria in s. NR 809.313 (2) to remain on
				  annual monitoring. The periodic required sanitary survey may be used to meet
				  the requirement for an annual site visit for the year in which the sanitary
				  survey was completed. Transient non-community systems with little-to-no
				  distribution system may, at the discretion of the department, be exempt from
				  the annual site visit requirements in this section, and still remain on annual
				  monitoring.
(dg)
Criteria
				  for annual monitoring at transient non-community systems.
Beginning
				  April 1, 2016, the department may reduce the monitoring frequency for a
				  well-operated transient non-community ground water system serving 1,000 persons
				  per day or fewer from quarterly routine monitoring to no less than annual
				  monitoring, if the transient non-community system demonstrates that it meets
				  the criteria for reduced monitoring in subds.
1. to 4., except for a transient
				  non-community system that has been on increased monitoring under the provisions
				  of sub. (2m). A transient non-community system on increased monitoring under
				  sub. (2m) shall meet the provisions of sub. (2m) (b) to go to quarterly
				  monitoring and shall meet the provisions of sub. (2m) (c) to go to annual
				  monitoring.
1. The transient
				  non-community system has a clean compliance history for a minimum of 12
				  months.
2. The most recent sanitary
				  survey shows that the transient non-community system is free of sanitary
				  defects or has corrected all identified sanitary defects, has a protected water
				  source, and meets approved construction standards.
3. The department has conducted an annual
				  site visit within the last 12 months and the water supplier has corrected all
				  identified sanitary defects. A Level 2 assessment that meets the criteria in s.
				  NR 809.313 (2) may be substituted for the department annual site
				  visit.
4. The public water system
				  is not a school.
(dr)
Seasonal system requirements.
1. Beginning April 1, 2016, all water
				  suppliers of seasonal systems shall demonstrate completion of a
				  department-approved start-up procedure, which may include a requirement for
				  start-up sampling prior to serving water to the public.
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).
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.
b.
				  To be eligible for quarterly monitoring, seasonal systems shall meet the
				  criteria in sub. (2m) (b).
c. To be
				  eligible for annual monitoring, seasonal systems shall meet the criteria under
				  sub. (2m) (c).
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.
(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.
(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.
(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.
(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.
(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.