Wisconsin Administrative Code
Department of Natural Resources
NR 800 - Environmental Protection - Water Supply
Chapter NR 809 - Safe Drinking Water
Subchapter II - Control of Lead and Copper
Section NR 809.548 - Monitoring requirements for water quality parameters

Universal Citation: WI Admin Code ยง NR 809.548

Current through August 26, 2024

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.

(1) GENERAL REQUIREMENTS.

(a) Sample collection methods.
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).

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.

(b) Number of samples.
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:

Public Water System Size (# People Served)

# of Sites For Water Quality Parameters

>100,000

25

10,001-100,000

10

3,301 to 10,000

3

501 to 3,300

2

101 to 500

1

<=100

1

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).

(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.

(a) At taps:
1. pH;

2. Alkalinity;

3. Orthophosphate, when an inhibitor containing a phosphate compound is used;

4. Silica, when an inhibitor containing a silicate compound is used;

5. Calcium;

6. Conductivity; and

7. Water temperature.

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

(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.

(a) At taps, 2 samples for:
1. pH;

2. Alkalinity;

3. Orthophosphate, when an inhibitor containing a phosphate compound is used;

4. Silica, when an inhibitor containing a silicate compound is used; and

5. Calcium, when calcium carbonate stabilization is used as part of corrosion control.

(b) Except as provided in par. (c), at each entry point to the distribution system, one sample every 2 weeks for:
1. pH;

2. When alkalinity is adjusted as part of optimal corrosion control, a reading of the dosage rate of the chemical used to adjust alkalinity and the alkalinity concentration; and

3. When a corrosion inhibitor is used as part of optimal corrosion control, a reading of the dosage rate of the inhibitor used and the concentration o forthophosphate or silica, whichever is applicable.

(c) The water supplier for a groundwater system can limit entry point sampling described in par. (b) to those entry points that are representative of water quality and treatment conditions throughout the public water system. If water from untreated groundwater sources mixes with water from treated groundwater sources, the water supplier shall monitor for water quality parameters both at representative entry points receiving treatment and representative entry points receiving no treatment. Prior to the start of any monitoring under this subsection, the water supplier shall provide to the department written information identifying the selected entry points and documentation, including information on seasonal variability, sufficient to demonstrate that the sites are representative of water quality and treatment conditions throughout the public water system.

(4) MONITORING AFTER THE DEPARTMENT SPECIFIES WATER QUALITY PARAMETER VALUES FOR OPTIMAL CORROSION CONTROL. After the department specifies the values for applicable water quality control parameters reflecting optimal corrosion control treatment under s. NR 809.543(6) and (7), water suppliers for all large systems shall measure the applicable water quality parameters in accordance with sub. (3) and determine compliance with the requirements of s. NR 809.543(8) every six months with the first six-month period to begin on either January 1 or July 1, whichever comes first, after the department specifies the optimal values under s. NR 809.543(6). Water suppliers for any small or medium-size systems shall conduct such monitoring during each six-month period specified in this paragraph in which the public water system exceeds the lead or copper action level. For any such small and medium-size system that is subject to a reduced monitoring frequency pursuant to s. NR 809.547(4) (d) at the time of the action level exceedance, the start of the applicable six-month monitoring period under this paragraph shall coincide with the start of the applicable monitoring period under s. NR 809.547(4) (d). Compliance with department designated optimal water quality parameter values shall be determined as specified under s. NR 809.543(8).

(5) REDUCED MONITORING.

(a) Water suppliers for any public water system that maintains the range of values for the water quality parameters reflecting optimal corrosion control treatment during each of 2 consecutive 6-month monitoring periods under sub. (4) shall continue monitoring at the entry points to the distribution system as specified in sub. (3) (b). Water suppliers for such public water systems may collect 2 tap samples for applicable water quality parameters from the following reduced number of sites during each 6-month monitoring period.

(# People Served) Public Water System Size

Reduced # of Sites for Water Quality Parameters

>100,000

10

10,001 to 100,000

7

3,301 to 10,000

3

501 to 3,300

2

101 to 500

1

<=100

1

(b)
1. Water suppliers for any public water system that maintains the range of values for the water quality parameters reflecting optimal corrosion control treatment specified by the department under s. NR 809.543(6) during 3 consecutive years of monitoring may reduce the frequency with which they collect the number of tap samples for applicable water quality parameters specified in par. (a) from every six months to annually. This sampling begins during the calendar year immediately following the end of the monitoring period in which the third consecutive year of six-month monitoring occurs. Water suppliers for any public water system that maintains the range of values for the water quality parameters reflecting optimal corrosion control treatment specified by the department under s. NR 809.543(6) during 3 consecutive years of annual monitoring under this paragraph may reduce the frequency with which they collect the number of tap samples for applicable water quality parameters specified in par. (a) of this section from annually to every 3 years. This sampling begins no later than the third calendar year following the end of the monitoring period in which the third consecutive year of monitoring occurs.

2. A water supplier for a public water system may reduce the frequency with which they collect tap samples for applicable water quality parameters specified in par. (a) to every 3 years if the public water system demonstrates during 2 consecutive monitoring periods that the public water system's tap water lead level at the 90th percentile is less than or equal to the practical quantitation limit for lead specified in s. NR 809.541(4) (a), that its tap water copper level at the 90th percentile is less than or equal to 0.65 mg/L for copper in s. NR 809.54(3) (b), and that it also has maintained the range of values for the water quality parameters reflecting optimal corrosion control treatment specified by the department under s. NR 809.543(6). Monitoring conducted every three years shall be done no later than every third calendar year.

(c) Water suppliers for any public water system that maintains the range of values for the water quality parameters reflecting optimal corrosion control treatment specified by the department under s. NR 809.543(6) during 3 consecutive years of annual monitoring may reduce the frequency with which they collect the number of tap samples for applicable water quality parameters specified in par. (a) from annually to every 3 years.

(d) A water supplier that conducts sampling annually shall collect these samples evenly throughout the year so as to reflect seasonal variability.

(e) Any water supplier that has a public water system subject to reduced monitoring frequency that fails to operate 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 809.543(8) shall resume distribution system tap water sampling in accordance with the number and frequency requirements in sub. (4). A water supplier may resume annual monitoring for water quality parameters at the tap at the reduced number of sites specified in par. (a) after they have completed 2 subsequent consecutive 6-month rounds of monitoring that meet the criteria of that paragraph or may resume triennial monitoring for water quality parameters at the tap at the reduced number of sites after the water supplier demonstrates through subsequent rounds or monitoring that the public water system meets the criteria of either par. (b) 1. or 2., or both.

Summary of Monitoring Requirements for Water Quality Parameters1

Monitoring period

Parameters2

Location

Frequency

Initial monitoring

pH, alkalinity, orthophosphate or silica3, calcium, conductivity, temperature.

Taps and at entry points to distribution system.

Every 6 months.

After installation of corrosion control

pH, alkalinity, orthophosphate or silica3, calcium4. pH, alkalinity, dosage rate and concentration (if alkalinity adjusted as part of corrosion control), inhibitor dosage rate and inhibitor residual5.

Taps

Entry points to the distribution system6.

Every 6 months.

No less frequently than every 2 weeks.

After department specifies parameter values for optimal corrosion control

pH, alkalinity, orthophosphate or silica3, calcium4. pH, alkalinity, dosage rate and concentration (if alkalinity adjusted as part of corrosion control), inhibitor dosage rate and inhibitor residual5.

Taps

Entry points to the distribution system6.

Every 6 months.

No less frequently than every 2 weeks

Reduced monitoring

pH, alkalinity, orthophosphate or silica3, calcium4.

pH, alkalinity, dosage rate and concentration (if alkalinity adjusted as part of corrosion control), inhibitor dosage rate and inhibitor residual5.

Taps

Entry points to the distribution system6.

Every 6 months, annually7or every 3 years8; reduced number of sites

No less frequently than every 2 weeks

1 Table is for illustrative purposes; consult the text of this section for precise regulatory requirements.

2 Water supplier for small and medium-size systems have to monitor for water quality parameters only during monitoring periods in which the public water system exceeds the lead or copper action level.

3 Orthophosphate must be measured only when an inhibitor containing a phosphate compound is used. Silica must be measured only when an inhibitor containing silicate compound is used.

4 Calcium must be measured only when calcium carbonate stabilization is used as part of corrosion control.

5 Inhibitor dosage rates and inhibitor residual concentrations (orthophosphate or silica) must be measured only when an inhibitor is used.

6 Water supplier for groundwater systems may limit monitoring to representative locations throughout the public water system.

7 Water suppliers for public water systems may reduce frequency of monitoring for water quality parameters at the tap from every 6 months to annually if they have maintained the range of values for water quality parameters in the public water system reflecting optimal corrosion control during 3 consecutive years of monitoring.

8 Water suppliers for public water systems may further reduce the frequency of monitoring for water quality parameters at the tap from annually to once every 3 years if they have maintained the range of values for water quality parameters in the public water system reflecting optimal corrosion control during 3 consecutive years of annual monitoring. Water suppliers for public water systems may accelerate to triennial monitoring for water quality parameters at the tap if the public water system has maintained 90th percentile lead levels less than or equal to 0.005 mg/L, 90th percentile copper levels less than or equal to 0.65 mg/L, and the range of water quality parameters designated by the department under s. NR 809.543(7) as representing optimal corrosion control during 2 consecutive 6-month monitoring periods.

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