§ 141.87 - Monitoring requirements for water quality parameters.

§ 141.87 Monitoring requirements for water quality parameters.

Cross Reference

Link to an amendment published at 86 FR 4300, Jan. 15, 2021.

Cross Reference

Link to an amendment published at 86 FR 14002, Mar. 12, 2021, delaying the above amendment.

Cross Reference

Link to an amendment published at 86 FR 31940, June 16, 2021, delaying the above amendment until Dec. 16, 2021.

All large water systems, and all small- and medium-size water systems that exceed the lead or copper action level shall , and all small- and medium-size water systems with corrosion control treatment that exceed the lead trigger level must 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.

(a) General requirements -

(1) Sample collection methods.

(i) Tap samples shall must 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 system, and seasonal variability. Tap sampling under this section is not required to be conducted at taps targeted for lead and copper sampling under § 141.86(a). Sites selected for tap samples under this section must be included in the site sample plan specified under § 141.86(a)(1). The site sample plan must be updated prior to changes to the sampling locations. [Note: Systems may find it convenient to conduct tap sampling for water quality parameters at sites used for total coliform sampling under 40 CFR § 141.21(a)(1) if they also meet the requirements of this section.]

(ii) Samples collected at the entry point(s) to the distribution system shall must be from locations representative of each source after treatment. If a system draws water from more than one source and the sources are combined before distribution, the system must 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).

(2) Number of samples.

(i) Systems shall must collect two tap samples for applicable water quality parameters during each monitoring period specified under paragraphs (b) through (e) of this section from the following minimum number of sites listed in table 1 to this paragraph (a)(2)(i).

System size (No. people served) No.

Systems that add sites as a result of the “find-and-fix” requirements in § 141.82(j) must collect tap samples for applicable water quality parameters during each monitoring period under paragraphs (b) through (e) of this section and must sample from that adjusted minimum number of sites. Systems are not required to add sites if they are monitoring at least twice the minimum number of sites list in table 1 to this paragraph (a)(2)(i).

Table 1 to paragraph (a)(2)(i)

System size (number people served)	Minimum number 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	≤ 100	1

(ii)

(A) Except as provided in paragraph (c)(

3

2) of this section, water systems

shall

without corrosion control treatment must collect two samples for each applicable water quality parameter at each entry point to the distribution system during each monitoring period specified in paragraph (b) of this section. During each monitoring period specified in paragraphs (c)

-

through (e) of this section, water systems

shall

must collect one sample for each applicable water quality parameter at each entry point to the distribution system.

(

b) Initial sampling All large water systems shall measure the applicable water quality parameters as specified below at taps and at

B) During each monitoring period specified in paragraphs (c) through (e) of the section, water systems with corrosion control treatment must continue to collect one sample for each applicable water quality parameter at each entry point to the distribution system

during each six-month monitoring period specified in § 141.86(d)(1). All small and medium-size systems shall measure the applicable water quality parameters at the locations specified below during each six-month monitoring period specified in § 141.86(d)(1) during which the system

no less frequently than once every two weeks.

(b) Initial sampling for water systems. Any large water system without corrosion control treatment must monitor for water quality parameters as specified in paragraphs (b)(1) and (2) of this section during the first two six-month tap sampling monitoring periods beginning no later than January 1 of the calendar year after the system either becomes a large water system, or fails to maintain their 90th percentile for lead below the PQL for lead. Any medium or small system that exceeds the lead or copper action level and any system with corrosion control treatment for which the State has not designated OWQPs that exceeds the lead trigger level shall monitor for water quality parameters as specified in paragraphs (b)(1) and (2) of this section for two consecutive 6-month periods beginning the month immediately following the end of the tap sampling period in which the exceedance occurred.

(1) At taps, two samples for:

(i) pH;

(ii) Alkalinity;

(

iii) Orthophosphate, when an inhibitor containing a phosphate compound is used;

(iv) Silica, when an inhibitor containing a silicate compound is used;

(v) Calcium;

(vi) Conductivity; and

(vii) Water temperature.

(2) At each entry point to the distribution system : all of the applicable parameters listed in paragraph (b)(1) of this section.

(c) Monitoring after installation of optimal corrosion control or re-optimized corrosion control treatment.

(1) Any

large

system

which

that installs

optimal

or modifies corrosion control treatment pursuant to § 141.81(d)(

4) shall measure the water quality parameters at the locations and frequencies specified below during each six-month monitoring period specified in § 141.86

5) or (e)(5) and is required to monitor pursuant § 141.81(d)(

2

6) or (

i). Any small or medium-size system which installs optimal corrosion control treatment shall conduct such monitoring during each six-month monitoring period specified in § 141.86(d)(2)(ii) in which the system exceeds the lead or copper action level.

(1e)(6) must monitor the parameters identified in paragraphs (c)(1)(i) and (ii) of this section every six months at the locations and frequencies specified in paragraphs (c)(1)(i) and (ii) of this section until the State specifies new water quality parameter values for optimal corrosion control pursuant to paragraph (d) of this section. Water systems must collect these samples evenly throughout the 6-month monitoring period so as to reflect seasonal variability.

(i) At taps, two samples each for:

(

i

A) pH;

(

ii

B) Alkalinity;

(

iii

C) Orthophosphate, when an inhibitor containing

a phosphate

an orthophosphate compound is used;

(

iv

D) Silica, when an inhibitor containing a silicate compound is used

; (v) Calcium, when calcium carbonate stabilization is used as part of corrosion control

.

(

2

ii) Except as provided in paragraph (c)(

3

1)(iii) of this section, at each entry point to the distribution system, at least one sample no less frequently than every two weeks (biweekly) for:

(

i

A) pH;

(

ii

B) 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

(

iii

C) 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 of orthophosphate or silica (whichever is applicable).

(

3

iii) Any

ground water

groundwater system can limit entry point sampling described in paragraph (c)(

2

1)(ii) of this section to those entry points that are representative of water quality and treatment conditions throughout the system. If water from untreated

ground water

groundwater sources mixes with water from treated

ground water

groundwater sources, the system must 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 paragraph (c)(1)(iii), the water system

shall

must provide to the State, 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 system.

(2) States have the discretion to require small and medium-size systems with treatment for which the State has not designated OWQPs that exceed the lead trigger level but not the lead and copper action levels to conduct water quality parameter monitoring as described in paragraph (c)(1) of this section or the State can develop its own water quality control parameter monitoring structure for these systems.

(d) Monitoring after State specifies water quality parameter values for optimal corrosion control.

(1) After the State specifies the values for applicable water quality

control

parameters reflecting optimal corrosion control treatment under § 141.82(f),

all large systems shall measure the applicable water quality parameters in accordance with paragraph (c) of this section

systems must monitor for the specified optimal water quality parameters during 6-month periods that begin on either January 1 or July 1. Such monitoring must be spaced evenly throughout the 6-month monitoring period so as to reflect seasonal variability and be consistent with the structure specified in paragraphs (c)(1)(i) through (iii) of this section.

(i) All large systems must measure the applicable water quality parameters specified by the State and determine compliance with the requirements of § 141.82(g) every six months with the first

six

6-month period to begin on either January 1 or July 1, whichever comes first, after the State specifies the optimal values under § 141.82(f).

(ii) Any small or medium-size

system shall conduct such

water system that exceeds an action level must begin monitoring during

each

the six-month period

specified in this paragraph in which the system

immediately following the tap sampling monitoring period in which the exceedance occurs and continue monitoring until the water system no longer exceeds the lead

or copper action level.

and copper action levels and meets the optimal water quality control parameters in two consecutive 6-month tap sampling monitoring periods under § 141.86(d)(3). For any such small and medium-size system that is subject to a reduced monitoring frequency pursuant to § 141.86(d)(4) at the time of the action level exceedance, the start of the applicable

six

6-month monitoring period under this paragraph

shall

must coincide with the start of the applicable tap sampling monitoring period under § 141.86(d)(4).

(iii) Compliance with State-designated optimal water quality parameter values

shall

must be determined as specified under § 141.82(g).

(2) Any small or medium-size system that exceeds the lead trigger level, but not the lead and copper action levels for which the State has set optimal water quality control parameters must monitor as specified in paragraph (d)(1) of this section every six month, until the system no longer exceeds the lead trigger level in two consecutive tap sampling monitoring periods.

(3) States have the discretion to continue to require systems described in paragraph (d)(2) of this section to monitor optimal water quality control parameters.

(e) Reduced monitoring.

(1) Any large water system that maintains the range of values for the water quality parameters reflecting optimal corrosion control treatment specified by the State under § 141.82(f) and does not exceed the lead trigger level during each of two consecutive six6-month monitoring periods under paragraph (d) of this section shall must continue monitoring at the entry point(s) to the distribution system as specified in paragraph (c)(21)(ii) of this section. Such system may collect two tap samples for applicable water quality parameters from the following reduced number of sites during each six6-month monitoring period. Water systems must collect these samples evenly throughout the 6-month monitoring period so as to reflect seasonal variability.

Table 2 to paragraph (e)(1)

System size (No. number of people served)	Reduced No. minimum number 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

(2)

(i) Any water system that maintains the range of values for the water quality parameters reflecting optimal corrosion control treatment specified by the State under § 141.82(f) and does not exceed the lead trigger level or copper action level during three consecutive years of monitoring may reduce the frequency with which it collects the number of tap samples for applicable water quality parameters specified in this paragraph (e)(1) of this section, 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 six6-month monitoring occurs. Any water system that maintains the range of values for the water quality parameters reflecting optimal corrosion control treatment specified by the State under § 141.82

(

f), during three consecutive years of annual monitoring under this paragraph may reduce the frequency with which it collects the number of tap samples for applicable water quality parameters specified in paragraph (e)(1) of this section from annually to every three 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.

(ii) A water system may reduce the frequency with which it collects tap samples for applicable water quality parameters specified in paragraph (e)(1) of this section to every three years year if it demonstrates during two consecutive monitoring periods that its tap water lead level at the 90th percentile is less than or equal to the PQL for lead specified in § 141.89 (a)(1)(ii), of 0.005 mg/L that its tap water copper level at the 90th percentile is less than or equal to 0.65 mg/L for copper in § 141.80(c)(23), and that it also has maintained the range of values for the water quality parameters reflecting optimal corrosion control treatment specified by the State under § 141.82(f). Monitoring conducted every three years shall be done no later than every third calendar year.

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

(4) Any water system subject to the reduced monitoring frequency that fails to operate at or above the minimum value or within the range of values for the water quality parameters specified by the State in § 141.82(f) for more than nine days in any six6-month period specified in § 141.82(g) shall must resume distribution system tap water sampling in accordance with the number and frequency requirements in paragraph (d) of this section. Such a system may resume annual monitoring for water quality parameters at the tap at the reduced number of sites specified in paragraph (e)(1) of this section after it has completed two subsequent consecutive six6-month rounds of monitoring that meet the criteria of that paragraph paragraph (e)(1) of this section and/or may resume triennial annual monitoring for water quality parameters at the tap at the reduced number of sites after it demonstrates through subsequent rounds of monitoring that it meets the criteria of either paragraph (e)(2)(i) or (e)(2)(ii) of this section.

(f) Additional monitoring by systems. The results of any monitoring conducted in addition to the minimum requirements of this section shall must be considered by the water system and the State in making any determinations (i.e., determining concentrations of water quality parameters) under this section or § 141.82.

Summary of Monitoring Requirements for Water Quality Parameters¹

Monitoring period Parameters² Location Frequency Initial monitoringpH, alkalinity, orthophosphate or silica³, calcium, conductivity, temperatureTaps and at entry point(s) to distribution systemEvery 6 months. After installation of corrosion controlpH, alkalinity, orthophosphate or silica³, calcium⁴ TapsEvery 6 months. pH, alkalinity, dosage rate and concentration (if alkalinity adjusted as part of corrosion control), inhibitor dosage rate and inhibitor residual⁵ Entry point(s) to distribution system⁶ No less frequently than every two weeks. After State specifies parameter values for optimal corrosion controlpH, alkalinity, orthophosphate or silica³, calcium⁴ TapsEvery 6 months. pH, alkalinity dosage rate and concentration (if alkalinity adjusted as part of corrosion control), inhibitor dosage rate and inhibitor residual⁵ Entry point(s) to distribution system⁶ No less frequently than every two weeks. Reduced monitoringpH, alkalinity, orthophosphate or silica³, calcium⁴ TapsEvery 6 months, annually⁷ or every 3 years⁸; reduced number of sites. pH, alkalinity dosage rate and concentration (if alkalinity adjusted as part of corrosion control), inhibitor dosage rate and inhibitor residual⁵ Entry point(s) to distribution system⁶ No less frequently than every two weeks.

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

² Small and medium-size systems have to monitor for water quality parameters only during monitoring periods in which the 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 Ground water systems may limit monitoring to representative locations throughout the system.

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

⁸ 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 reflecting optimal corrosion control during 3 consecutive years of annual monitoring. Water systems may accelerate to triennial monitoring for water quality parameters at the tap if they have 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 State under § 141.82(f) as representing optimal corrosion control during two consecutive six-month monitoring periods.

[56 FR 26548, June 7, 1991; 57 FR 28788, June 29, 1992, as amended at 59 FR 33862, June 30, 1994; 65 FR 2010, Jan. 12, 2000; 72 FR 57818, Oct. 10, 2007

(g) Additional sites added from find-and-fix. Any water system that conducts water quality parameter monitoring at additional sites through the “find-and-fix” provisions pursuant to § 141.82(j) must add those sites to the minimum number of sites specified under paragraphs (a) through (e) of this section unless the system is monitoring at least twice the minimum number of sites.

[86 FR 4300, Jan. 15, 2021]