PA United States Environmental Protection Agency Per- and Polyfluoroalkyl Substances Compliance Monitoring: A Quick Reference Guide Overview Rule Title Per- and Polyfluoroalkyl Substances (PFAS) National Primary Drinking Water Regulation 89 FR 32532, April 26, 2024, Vol. 89, No. 82 Focus of This Guide This document describes how to determine the compliance monitoring frequency under the PFAS Rule. Utilities Covered The PFAS Rule applies to all community water systems (CWSs) and non-transient non- community water systems (NTNCWSs), hereafter referred to collectively as water systems. Key Milestones April 26, 2027: Initial monitoring ends and compliance monitoring begins. April 26, 2029: All regulated water systems must comply with the PFAS MCLs. Code of Federal Regulations (CFR) Citations See the following sections in Title 40, Part 141 of the CFR: ~ For PFAS regulations, see Subpart Z. Analytical requirements in 40 CFR 141.901 also apply. ~ For Maximum Contaminant Levels (MCLs), see 40 CFR 141.61 (c)(2). ~ For Maximum Contaminant Level Goals, see 40 CFR 141.50. ~ For compliance dates, see 40 CFR 141.6(1) and 40 CFR 141.900(b). Key Terms Reliably and Consistently Reliably and consistently below the MCL means that each of the samples contains regulated PFAS concentrations below the applicable MCLs. For the PFAS Rule, this demonstration of reliably and consistently below the MCL would include consideration of at least four quarterly samples at an entry point below the MCL, but primacy agencies will make their own determination as to whether the detected concentrations are reliably and consistently below the MCL (89 FR 32660-32661, footnotes 21 and 23). Trigger Levels The trigger levels are used to determine an appropriate monitoring frequency and are set at one-half of the MCLs for regulated PFAS, including the Hazard Index MCL for mixtures of PFHxS, HFPO-DA, PFNA, and/or PFBS (see 40 CFR 141.902(a)(5)). General Compliance Monitoring Requirements (40 CFR 141.902) Primacy agencies use initial monitoring results to establish sampling schedules for the start of the compliance monitoring period on April 26, 2027. (For more information, see section below on Compliance Monitoring Frequencies and Eligibility Requirements, as well as Per- and Polyfluoroalkyl Substances Initial Monitoring: A Quick Reference Guide at https://www.epa.qov/svstem/files/docuinents/2024-12/pfas-iriitialmonitorina-grg-dec24. Bdt) The compliance monitoring frequency and schedule is specific to each individual entry point to the distribution system (entry point). A primacy agency (a state, territory, Tribal Nation, or EPA Region with oversight responsibilities for the National Primary Drinking Water Regulation) may require a water system to have multiple sampling schedules, one per entry point, based on past results. Compliance monitoring begins on April 26, 2027. The first quarterly compliance monitoring period will end on June 30, 2027, and the first triennial monitoring period will end on December 31, 2029. Annual monitoring is only allowed when an entry point is deemed reliably and consistently below the MCL. During compliance monitoring, each water system must sample at the time designated by the primacy agency within each monitoring period. The monitoring schedule at an entry point must be the same for all regulated PFAS and is based on the most frequent sampling required for any regulated PFAS (40 CFR 141,902(b)(2)(iv)). The water system must sample at an entry point during periods of normal operating conditions (40 CFR 141.902(a) (1))- If the water system draws water from multiple sources that are combined before distribution, the water system must sample at an entry point during periods of representative operating conditions (40 CFR 141.902(a)(2)). Each water system must ensure that all results provided by a laboratory are reported to the primacy agency and used for determining required sampling frequencies. This includes values below the trigger levels and practical quantitation levels; zero must not be used in place of reported values (40 CFR 141.902(a)(7)). Analytical Requirements for Compliance Monitoring (40 CFR 141.901(b)) Use of Certified Laboratories: ~ Analyses for regulated PFAS must be conducted by laboratories that have been certified by the EPA or the primacy agency. Lab certification requirements are specified in 40 CFR 141.901(b)(2). ~ A certified laboratory must report data for concentrations as low as the trigger levels, beginning June 25, 2024 (40 CFR 141.901 (b)(2)(iii)). Approved Analytical Methods: ~ EPA Method 533 ~ EPA Method 537.1 (Version 1.0 or 2.0 may be used for initial monitoring; only Version 2.0 is specified for the compliance monitoring that begins April 2027) ------- Per- and Polyfluoroalkyl Substances Compliance Monitoring: A Quick Reference Guide Regulatory Thresholds (40 CFR 141.902(a)(5); 40 CFR 141.61(c)) Trigger Levels and Maximum Contaminant Levels (MCLs) for PFAS Contaminants: Contaminant Trigger Level (1/2 MCLs) MCLs Levels (in parts per trillion (ppt), unless otherwise noted) PFOA 2.0 4.0 PFOS 2.0 4.0 HFPO-DA (or GenX chemicals) 5 10 PFHxS 5 10 PFNA 5 10 Hazard Index PFAS (mixtures of two or more of HFPO-DA, PFBS, PFHxS, PFNA) 0.5 (unitless) 1 (unitless) ~ Note that the trigger levels and MCLs for PFOA and PFOS have two significant figures whereas all other contaminants only have one. ~ If any sample result is at or above the trigger level, the water system must shift to quarterly monitoring at that entry point for all PFAS, unless the primacy agency has made a determination that results are reliably and consistently below the MCL and the latest results do not change that determination (this exception applies to Annual Monitoring as discussed below). Compliance Monitoring Frequencies and Eligibility Requirements (40 CFR 141.902(b)(2)): Quarterly Monitoring ~ A primacy agency will direct a water system to begin quarterly monitoring at an entry point if any of the following apply: ~ Any regulated PFAS concentration is at or above a trigger level during initial monitoring. ~ Any regulated PFAS concentration is at or above a trigger level during compliance monitoring and a primacy agency has not determined that all regulated PFAS at the entry point are reliably and consistently below the regulated PFAS MCLs. ~ Any regulated PFAS concentration is at or above the MCL during annual monitoring, or the primacy agency otherwise determines that a sampling point where monitoring has been occurring on an annual basis is no longer reliably and consistently below the regulated PFAS MCLs. ~ Samples must be collected in four consecutive quarters at a time designated by the primacy agency during the monitoring period. ~ The first annual or triennial sample that triggered quarterly monitoring is considered the first quarterly sample for the purposes of determining compliance with the MCLs.1 Annual Monitoring ~ Allowed when the primacy agency determines that all quarterly sample results at an entry point are reliably and consistently below the MCL based on at least four consecutive quarters of data collected during the compliance monitoring period for all regulated PFAS. ~ Annual monitoring is performed in the quarter in which the highest analytical result was detected during the most recent round of quarterly monitoring. ~ Note: No water system may begin entry-point compliance monitoring in April of 2027 on an annual monitoring schedule; monitoring frequency at that point in time will either be triennial, if conditions are met, or quarterly. Triennial Monitoring ~ Monitoring is performed in the quarter in which the highest analytical result was detected during the most recent round of quarterly sampling (or semi-annual monitoring, if no quarterly sampling has occurred). ~ A primacy agency may permit a system to conduct triennial sampling at an entry point if: ~ At the start of compliance monitoring, no regulated PFAS are present at or above any trigger level during initial monitoring; ~ During compliance monitoring, the previous triennial sample does not contain any regulated PFAS at concentrations at or above trigger levels; or ~ During compliance monitoring, no annual samples for three consecutive years contain any regulated PFAS at concentrations at or above trigger levels. ------- PA United States Environmental Protection Agency For additional information on the PFAS Rule Please visit the EPA PFAS NPDWR implementation Web site at https://www.epa gov/dwreainfo/pfas-rule- implementation or contact your drinking water primacy agency. Per- and Polyfluoroalkyl Substances Compliance Monitoring: A Quick Reference Guide Compliance Monitoring Frequencies and Eligibility Requirements (40 CFR 141.902(b)(2)): Cont. When a water system reduces its sampling frequency to annual or triennial sampling, the next compliance sample must be collected in the monitoring period that begins the calendar year following primacy agency approval of a reduction in monitoring frequency (40 CFR 141.902(b)(2)(viii)). The primacy agency may increase the required monitoring frequency, where necessary, to detect variations within a water system (e.g., fluctuations due to seasonal use, changes in water source) (40 CFR 141,902(b)(2)(vi)). Primacy agencies may require confirmation samples. When this occurs, results from the original sample and confirmation sample collected during the same monitoring period are considered individually (i.e., not averaged) to determine whether any sample result was at or above a trigger level. Results from the two samples are averaged only to determine the value to be used in the running annual average (RAA) calculation to assess MCL compliance (40 CFR 141.902(b)(2)(v)). 1 Compliance is determined based on the RAA for an entry point at which a water system is conducting quarterly monitoring. For more information about compliance determinations, see Per- and Polyfluoralkyl Substances Compliance Determination: A Quick Reference Guide at https://www.epa.aov/svstem/files/documents/2025-01/pfas- compliance-determination-arg-ian25.pdf. Compliance Monitoring Reporting (40 CFR 141.31; 40 CFR 141.904(b)) Water systems must report to the primacy agency: General Reporting ~ The monitoring results within the shorter of: ~ The first 10 days following the month in which the result is received by the water system (40 CFR 141.31(a)(1)), or ~ The first 10 days following the end of the required monitoring period, as stipulated by the primacy agency (40 CFR 141.31 (a)(2)). ~ Failure to comply with any rule requirement within 48 hours (including failure to comply with monitoring requirements) (40 CFR 141.31(b)). For Water Systems on Quarterly Monitoring ~ All sample results, including the locations, number of samples taken at each location, dates, and concentrations during the previous quarter. ~ The RAA at each sampling point of all compliance samples. ~ Whether a result is at or above any trigger level in any samples. ~ Wnether a result is at or above an MCL for a regulated PFAS in any samples. ~ Whether an MCL was violated (i.e., an RAA above the MCL). For Water Systems Monitoring Less Frequently than Quarterly ~ All sample results, including the locations, number of samples taken at each location, dates, and concentrations during the previous monitoring period. ~ Whether a result was at or above a trigger level for a regulated PFAS in any samples. ~ Whether a result was at or above an MCL for a regulated PFAS in any samples (a monitoring frequency consideration). ~ Whether a single result is such that an RAA will violate the MCL (e.g., the results from a single sample are more than four times the MCL for any regulated PFAS, yielding an RAA exceedance independent of the other quarterly results). Note: The statutory provisions and the EPA regulations described in this document contain legally binding requirements. This document is not a regulation itself, nor does it change or substitute for those provisions and regulations. Office of Water (4606M) EPA810F25015 http://water.epa.gov/drink January 2025 ------- |