Requirements and Best Practices for the Collection
and Analysis of Samples for the PFAS National Primary
Drinking Water Regulation
Background
In April 2024, the EPA published a National Primary Drinking Water Regulation (NPDWR) for Per- and
Polyfluoroalkyl Substances (PFAS) ("the PFAS Rule"). The rule sets nationwide Maximum Contaminant Levels
(MCLs) for five individual PFAS: PFOA, PFOS, PFNA, PFHxS, and HFPO-DA (or "GenX Chemicals"). It also
sets a Hazard Index MCL for mixtures containing two or more of four PFAS: PFHxS, PFNA, HFPO-DA, and
PFBS. In support of the initial monitoring required by the rule (to be completed by April 26, 2027) and the ongoing
compliance monitoring thereafter, this document provides requirements and guidance for the collection, handling,
and analysis of samples. The PFAS Rule requires the use of methods approved under 40 CFR 141.901 during
the compliance monitoring period and under 40 CFR 141.901 or Appendix A to Subpart C of Part 141 during initial
monitoring.
PFAS Sampling Kit Requirements
A sample set is defined as samples collected from the same sample collection site at the same time. If a water
system is responsible for PFAS compliance monitoring at multiple wells, then they are required to collect a field
sample and prepare a companion Field Reagent Blank (FRB) for each one of those wells. If a water system is
responsible for PFAS compliance monitoring at multiple entry points to the distribution system, then the water
system must collect a field sample and prepare a companion FRB for each entry point.
Sampling kits for each site must contain a minimum of 3 bottles per sampling site, with approximately 10% of
sampling kits containing 2 additional bottles for the preparation of laboratory fortified sample matrix (LFSM) and
LFSM duplicate (LFSMD) Quality Control (QC) samples at the laboratory. Sampling kits must use polypropylene
bottles fitted with polypropylene screw-caps, polyethylene bottles with polypropylene screw-caps, or other plastic
materials that meet QC requirements. Aqueous samples should not come into contact with glass. Sample bottles
are defined as:
~ Afull FRB bottle: a sealed, unpreserved bottle of PFAS-free reagent water.
~ Reagent water used for the FRBs must be analyzed prior to shipment to ensure the water is PFAS-free
meeting Laboratory Reagent Blank (LRB) method criteria (i.e., no PFAS levels greater than 1/3 of the
laboratory-specific minimum reporting level (MRL).
An empty but "preserved" FRB bottle: an empty bottle containing sample preservatives.
~ The same lot of preservative must be used for the FRBs as for the Field Sample.
~ An empty but "preserved" Field Sample (FS) bottle: an empty bottle containing sample preservatives.
If used, reusable ice packs for maintaining sample temperature during shipment to the laboratory must be verified
to be free of PFAS contamination. Sample kits must be able to maintain the temperature of the collected FRB and
FSs such that samples are below 10°C when received by the laboratory.
Laboratories and Programs Preparing Sampling Guidance Should Be
Aware of These Sampling Precautions
PFAS are found in thousands of products we use every day, and contamination could be accidentally introduced
into samples during sampling. Sampling instructions provided to samplers should follow the precautions listed
below to minimize the possibility of contaminating samples. The following guidance is based upon the EPA's
experience in sample collection under the Fifth Unregulated Contaminated Monitoring Rule (UCMR 5). The EPA
provided this video to assist with sample collection under UCMR 5 but be aware that this video also includes
instructions specific to the UCMR 5 sampling kit. Laboratories may provide kits that are different than those used in
UCMR 5. UCMR 5 Sample Collection Training Video for Small Public Water Systems
Samplers should NOT
~ Apply personal care products, sunscreen, or insect repellant prior to sample collection.
~ Use anti-fog sprays or wipes prior to sample collection.
~ Handle or use water-, oil-or stain-resistant materials prior to sample collection (i.e., water-repellant face
masks, food packaging and wrappers, Gore-Tex orTyvek clothing, plastic clipboards).
~ Use permanent markers (i.e., Sharpies) to label sample bottles.
~ Touch the inside of the cap or bottle.
~ Touch the bottle to the faucet.
~ Place the lids in a pocket (set bottle lids face up on a clean surface while sampling).
~ Rinse out or overfill sampling bottles. Sampling bottles contain preservatives that need to be dissolved into the
sample.
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Requirements and Best Practices for the Collection
and Analysis of Samples for the PFAS National Primary
Drinking Water Regulation
Laboratories and Programs Preparing Sampling Guidance Should Be
Aware of These Sampling Precautions Cont.
Samplers MUST
~ Wash their hands before handling sample bottles.
~ Wear nitrile gloves when filling and sealing sample bottles.
~ Collect a FRB at each sampling site.
Put on a new pair of gloves.
Samplers are to pour the bottle containing reagent water into the FRB blank bottle, cap and shake for 15
seconds.
Record sampling information as directed by the laboratory, including date, time and sampling location.
Dispose of gloves.
Collect a Field Sample (FS) at each sampling site.
If present, remove any aerators, hoses, tubing and/or Teflon tape from the faucet.
Open and flush the valve to obtain a sample representative of the water entering the distribution system.
Reduce the stream to pencil thickness.
Put on a new pair of nitrile gloves.
Uncap the FS bottle, fill to just below the neck, and recap the bottle.
Record sampling information as directed by the laboratory, including date, time and sampling location.
~ FRB and FS must be stored at <6°C, but not frozen.
~ Sampling kits must arrive at the laboratory within 2 days/48 hours of collection.
Laboratory Sample Receipt and Sample Storage Requirements
Laboratories MUST
~ Establish sample receipt procedures to verify FRB and FS were properly preserved including:
~ Confirming sample temperature is below 10°C when received by the lab.
~ Samples are received within 2 days/48 hours from collection,
~ Verifying sample pH of 6 to 8.
~ Verifying absence of free chlorine.
~ Invalidate and recollect FRB and FS that do not meet sample receipt criteria.
Verification of free chlorine: The verification of the "absence" of free chlorine is qualitative, provided the laboratory
can measure the presence of free chlorine at and above 0.1 mg/L. Note that a small separate aliquot of the sample
should be used to test pH and chlorine content. To prevent sample contamination, probes and test strips cannot
be placed Into the bulk sample bottle. When a positive free chlorine result occurs, the method requires that it be
rechecked with a second technique, such as the free chlorine DPD (diethyl-p-phenylene diamine) method. Be sure
to collect enough sample volume (fully filling bottle to just below the neck) to account for the free chlorine tests
and any other measurement, such as for pH. Laboratories are cautioned that using DPD reagents or test strips for
the verification of the absence of free chlorine can exhibit a false positive bias due to the presence of chioramine
(which can be expected in samples collected from water systems employing chioramine disinfection). To minimize
this false positive potential, laboratories must evaluate results immediately (less than 1 second) after the sample
is allowed to react with the DPD reagent/test strip. Color changes occur over time, and delayed readings lead to
erroneous results.
Laboratories must NOT
~ Use glass sampling bottles or pipettes, as PFAS analytes can adsorb to glass surfaces.
~ Add additional preservative to FRB or FS that do not meet sample receipt criteria,
~ Place probes or test strips into the bulk sample collection bottle.
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Requirements and Best Practices for the Collection
and Analysis of Samples for the PFAS National Primary
Drinking Water Regulation
PFAS Analysis Requirements
Laboratories MUST
Laboratories must only use the methods approved in 40 CFR 141.901 and must adhere to method flexibilities
allowed in the approved methods. Generally, method flexibilities include: the use of different liquid chromatography
columns, modifying liquid chromatography and mass spectrometry conditions, and the use of some consumables,
if method performance is improved.
Laboratories wishing to analyze samples required by an NPDWR must be "certified" by a primacy agency, typically
the state. Laboratory certification programs, including comparable state laboratory "NELAP accreditation" programs
that use the TNi Standard, are referred to herein as "certification programs" for simplicity.
Laboratories must be audited by a certification program on a triennial basis to analyze samples under the PFAS
Rule.
Laboratories must conduct an Initial Demonstration of Capability (IDC) prior to analyzing samples under the PFAS
Rule, and after any allowed modification to the approved methods. Method IDCs require laboratories to determine
a laboratory-specific MRL. The laboratory MRL must be less than or equal to the Practical Quantitation Level
(PQL) defined in 40 CFR 141,903(f)(1)(iv) (this is different from a Practical Quantitation Limit, as defined at 40 CFR
141.2). The PQL represents the lowest level at which a contaminant can be reliably quantified within specific limits
of precision and accuracy (see 40 CFR 141.902(a)(7)).
Laboratories must pass at least one Water Supply (WS) Proficiency Testing (PT) study, sometimes referred
to as a Performance Evaluation (PE) Study, per year, pursuant to the requirements in 40 CFR 141.901 (b)(2)
(i). Laboratories must successfully analyze the six regulated PFAS in the same PT study. If the laboratory fails
the PT study for any one of the regulated PFAS analytes, the laboratory must participate in the next available
PT study and analyze and report passing results for all six PFAS. This is warranted to satisfy compliance with
calculating and reporting the Hazard Index that requires certified lab results for PFHxS, PFNA, HFPO-DA, and
PFBS. Laboratories may use any PT provider acceptable to the primacy agency, including PT providers accredited
through the TNI Proficiency Testing Program.
Laboratories must NOT
Laboratories may not make modifications to the approved methods outside of the procedural and instrument
flexibilities that are described within the methods. Laboratories must not make changes to sample preservation
requirements, quality control requirements, or to the extraction procedures described in the approved methods.
Field Reagent Blank Analysis Requirements
If a field sample contains any method analyte at, or above, the required method MRL, the laboratory must analyze
the FRB that was prepared concurrent with the collection of the field sample. To be acceptable, an FRB must have
analyte concentrations that are less than one-third the MRL. If an FRB does not meet this criterion, sampling must
be repeated.
Table 1: FRB Requirements for PFAS Analyses
Contaminant
PQL (parts per
trillion or ppt)1
Laboratory
Specific MRL2
(PPt)
FRB and LRB criteria3 (ppt)
PFOA
4.0
A
II
-N
o
1/3 laboratory specific MRL
(e.g., <= 1.3)
PFOS
4.0
A
II
b
1/3 laboratory specific MRL
(e.g., <= 1.3)
PFHxS
3.0
A
II
CO
b
1/3 laboratory specific MRL
(e.g., <= 1.0)
PFNA
4.0
A
II
b
1/3 laboratory specific MRL
(e.g., <= 1.3)
HFPO-DA
5.0
A
II
Ol
b
1/3 laboratory specific MRL
(e.g., <= 1.7)
PFBS
3.0
A
II
CO
b
1/3 laboratory specific MRL
(e.g., <= 1.0)
1 All PQLs have two significant figures.
2 Laboratory-specific MRLs are calculated by the laboratory in the IDC. The laboratory-specific MRL MUST be less
than or equal to the PQL specified in 40 CFR 141,903(f)(1 )(v).
3 The FRB and LRB criteria are 1/3 the laboratory specific MRL. On each row, there is an example shown. For these
examples, the laboratory specific MRL is equal to the PQL.
Note: The units shown in this table are in ppt, equivalent to nanograms per liter (ng/L).
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Requirements and Best Practices for the Collection
and Analysis of Samples for the PFAS National Primary
Drinking Water Regulation
Laboratory Certification Requirements
Laboratories wishing to analyze samples required by an NPDWR must be "certified" by the primacy agency, typically
the state. State laboratory "NELAP accreditation" programs using the TNI Standard, are considered equivalent
to state certification programs. Such certification programs that wish to assess laboratories to support PFAS
monitoring pursuant to the PFAS Rule must incorporate procedures into their program that allow them to judge
laboratory conformance with the methods approved under 40 CFR 141.901. This includes an on-site audit by the
primacy agency on at least a triennial basis. The EPA supports and encourages secondary certification/accreditation
through recognition of one primacy agency's primary certification by another primacy agency (i.e., reciprocity or
reciprocal certification).
To assist primacy agencies in auditing laboratories, the EPA has added PFAS-specific Certification Officer (CO)
Training into the EPA's annual CO training course for organic chemistry. This training addresses key elements of
the PFAS Rule and the approved PFAS methods. COs wishing to evaluate laboratory conformance with the PFAS
Rule and approved PFAS methods are expected to successfully complete the EPA CO training course for organic
chemistry.
Certification programs must verify that laboratories are appropriately analyzing samples with one of the methods
approved under 40 CFR 141.901 (EPA533; EPA537.1, V2.0). On January 16, 2025, the EPAapproved an
additional alternative PFAS Method (EPA 537.1, N/1.0) specifically to meet initial monitoring requirements (40 CFR
141,902(b)(1) [Monitoring requirements for PFAS—Initial monitoring]. This allows historical PFAS monitoring data
collected since January 2019 and analyzed using EPA 537.1, V1.0 to conditionally satisfy some or all of the initial
monitoring requirements (90 FR 4658) if other regulatory requirements are met. Samples collected for purposes of
compliance with the PFAS Rule, beginning April 26, 2027, must not be analyzed using EPA 537.1, V1.0.
Per to the requirements in 40 CFR 141.901 (b)(2)(i), laboratories are required to pass at least one Proficiency
Testing (PT) study, sometimes referred to as a Performance Evaluation (PE) Study, per year. The PT acceptance
limits are listed in Table 2.
Table 2. PFAS Proficiency Testing Acceptance Limits
Contaminant
Acceptance limits
(percent of true value)
PFOA
70-130
PFOS
70-130
PFHxS
70-130
PFNA
70-130
HFPO-DA
70-130
PFBS
70-130
Additional information regarding laboratory certification requirements for the initial monitoring period can be found
in the memorandum issued on November 21, 2024, titled "PFAS National Primary Drinking Water Regulation
Monitoring and Reporting."
Questions regarding this document may be directed to DWLabCert@epa.oov.
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v>EPA
United States
Environmental Protection
Agency
Requirements and Best Practices for the Collection
and Analysis of Samples for the PFAS National Primary
Drinking Water Regulation
References
Burneson, E. and Echeverria, M. 2024. PFAS National Primary Drinking Water Regulation Monitoring and
Reporting. Memorandum to UCMR 5 Laboratories, UCMR 5 Drinking Water Systems, EPA Regional Laboratory
Directors and State Laboratory Certification Officers. November 21, 2024. https://www.epa.aov/svstem/files/
documents/2024-11/memorandum-on-final-pfas-nDdwr-monitorina-and-reDortina for-iabs-and-svstems pdf
California State Water Quality Control Board. 2020. Per- and Polyfluoroalkyl Substances (PFAS) Sampling
Guidelines for Non-Drinking Water. September 2020. https://www.waterboards.ca.aov/pfas/docs/sept 2020 pfas
sampling auidelines.pdf
Massachusetts Department of Environmental Protection (MassDEP). 2021. Field Sampling Guide for PFAS Using
EPA Method 537 or 537.1. June 2021. https://www.mass.aov/doc/field-samplina-auide-for-pfas/download
Mills, M. 2018. Per- and Polyfluoroalkyl Substances (PFAS): Source/Site Characterization and Treatment/
Remediation. Emerging Contaminants Summit 2018, Westminster, CO, March 06-07, 2018. https://cfpub.epa.aov/
si/si public record report.cfm?Lab=NRMRL&dirEntrvld=345374
USEPA. 2018. Method 537.1: Determination of Selected Per- and Polyfluorinated Alkyl Substances (PFAS) in
Drinking Water by Solid Phase Extraction and Liquid Chromatography/Tandem Mass Spectrometry (LC/MS/MS).
Version 1.0. EPA/600/R-18/352. November 2018.
USEPA. 2019. Method 533: Determination of Per- and Polyfluoroalkyl Substances in Drinking Water by Isotope
Dilution Anion Exchange Solid Phase Extraction and Liquid Chromatography/Tandem Mass Spectrometry. 815-B-
19-020. November 2019.
USEPA. 2020. Method 537.1: Determination of Selected Per- and Polyfluorinated Alkyl Substances in Drinking
Water by Solid Phase Extraction and Liquid Chromatography/ Tandem Mass Spectrometry (LC/MS/MS). Version
2.0. EPA/600/R-20/006. March 2020.
USEPA 2022. Per- and Polyfluoroalkyl Substances (PFAS) Tribal Drinking Water Sampling Project. EPA Pacific
Southwest (Region 9). https://www.epa.aov/svstem/files/documents/2022-06/r9-trlbai-drinkina-water-samplina-
proiect-directions-for-pfas-sainple-collection.pdf
For additional
information on the
PFAS Rule
Please visit the EPA PFAS
NPDWR implementation
Web site at https://www.epa.
aov/dwreainfo/pfas-rule-
implementation or contact
your primacy agency drinking
water representative.
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. The
examples included
in this document are
intended for informational
purposes only.
'" '\
EPA 810-F-24-049
http://water.epa.aov/drink
December 2024 (Updated February 2025)
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