EPA PFAS Drinking Water Laboratory Methods
Using EPA methods 533 and 537.1, both government and private laboratories can now effectively measure 29 PFAS in their drinking water.
- 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
- 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)
- Method 537: Determination of Selected Perfluorinated Alkyl Acids in Drinking Water by Solid Phase Extraction and Liquid Chromatography/Tandem Mass Spectrometry (LC/MS/MS)
- Table: Comparing EPA Analytical Methods for PFAS in Drinking Water
Questions and Answers
What methods has EPA published to support the analysis of PFAS in drinking water?
EPA has developed, validated, and published three methods to support the analysis of 29 PFAS in drinking water, Method 533, 537 and 537.1.
Must EPA methods be used to analyze drinking water samples for PFAS for UCMR 5 and the PFAS Drinking Water Regulation Compliance?
Yes, EPA’s drinking water analytical methods were developed with particular attention to accuracy, precision, and robustness and have been through multi-lab validation and peer review. EPA’s Method 537.1, Rev 2.0 (2020) and EPA Method 533 (2019) are approved for monitoring PFAS under the fifth Unregulated Contaminant Monitoring Rule (UCMR 5, 2023-2025) and were promulgated as the only currently approved methods to monitor PFAS under the PFAS National Primary Drinking Water Regulation (NPDWR).
Must testing laboratories be state-“certified” to analyze drinking water for PFAS in compliance samples under the PFAS Drinking Water Regulation? Are state-certified laboratories available?
States generally certify laboratories that support drinking water compliance monitoring (i.e., for regulated contaminants). The PFAS NPDWR includes mandated requirements for the certification of laboratories to monitor the regulated PFAS specified in the rule. EPA is aware that some states currently offer certification/accreditation programs for the analysis of drinking water samples using EPA PFAS methods and all primacy states will be establishing PFAS laboratory certification programs to support the required monitoring. More details about PFAS NPDWR compliance can be found in the PFAS Monitoring and Reporting Fact Sheet and the final rule, which describe both the “initial monitoring” and “on-going compliance monitoring” provisions along with state discretionary options on initial monitoring data.
How can I find a lab to analyze my drinking water samples?
Public water systems or individual homeowners should contact their state laboratory certification program to learn if the state has already certified laboratories for PFAS analysis or has other recommendations to test for PFAS while the state establishes a PFAS laboratory certification program.
Can I use other PFAS Methods for drinking water samples that are not for the UCMR 5 or compliance with the PFAS Drinking Water Regulation?
Techniques other than Methods 537.1 and 533 may be appropriate for the analysis of PFAS in drinking water but they have not been evaluated by EPA and are not approved for UCMR 5 or the PFAS NPDWR. Those considering alternative methods (for purposes other than UCMR 5 or NPDWR monitoring) should consider the degree to which method performance has been evaluated and documented, as well as the degree to which the method capabilities align with project-specific objectives that will be used to assess data quality.
Are EPA’s drinking water methods appropriate for the analysis of PFAS in groundwater samples?
EPA’s methods were developed and validated for the analysis of finished drinking water (i.e., potable water) from both groundwater and surface water sources. Test samples evaluated during method development for each of the three EPA PFAS methods included groundwater samples from challenging water matrices. The groundwater sample matrices had very high total dissolved solids (TDS)/hardness (up to 300 mg/L). The evaluation of the groundwater matrices generated acceptable method performance data that met stringent, method-defined quality control criteria. These EPA methods are therefore effective for analyzing PFAS in ambient groundwater samples that may be used as drinking water.
What are “modified EPA PFAS methods” (e.g., “Modified Method 537”) and can they be used effectively for analysis of drinking water samples?
EPA is aware of some laboratories that are offering analysis for PFAS by techniques described as “modified” (e.g., “Modified Method 537”). These modified methods are sometimes offered by laboratories to assess samples of drinking water and other environmental media (e.g., soils, ambient water) and to address PFAS analytes not currently addressed by EPA’s methods. EPA is not aware of a standardized description of the modified methods, nor is the Agency aware of studies that have validated the performance of these modified methods across multiple laboratories. Therefore, EPA cannot address the performance of “modified methods” in a general manner. If you are considering using a modified method to analyze a sample (for purposes other than UCMR 5 or NPDWR monitoring), EPA recommends that you evaluate its appropriateness relative to your goals for the data and data quality objectives.