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PFOA, PFOS and Other PFASs

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.

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?

EPA’s methods were developed with particular attention to accuracy, precision, and robustness and have been through multi-lab validation and peer review. Method 537 was used extensively during Unregulated Contaminant Monitoring Rule 3. Techniques other than Methods 537, 537.1, and 533 may be appropriate for the analysis of PFAS in drinking water but they have not been evaluated by EPA. Those considering alternative methods 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, EPA recommends that you evaluate its appropriateness relative to your goals for the data and data quality objectives.

What method(s) does EPA recommend for the analysis of HFPO-DA (the “Gen X” chemical) in drinking water?

EPA Methods 537.1 and 533 have been validated for the analysis of HFPO-DA (a component of the GenX processing aid technology). EPA’s Office of Water has not evaluated other methods that may be offered for the analysis of HFPO-DA. 

Must testing laboratories be state-“certified” to analyze drinking water for PFAS? Are state-certified laboratories available?

States generally certify laboratories that support drinking water compliance monitoring (i.e., for regulated contaminants). EPA does not currently regulate PFAS under the Safe Drinking Water Act and therefore does not have any laboratory certification requirements for PFAS. EPA is aware that some states offer programs for laboratories that wish to be certified to analyze drinking water samples using EPA PFAS methods. EPA is also aware that ISO 17025 accreditation bodies (“ILAC signatories”) offer such service for laboratories conducting non-regulatory monitoring or testing (such as PFAS testing). Lastly, EPA is aware that DOD manages a PFAS laboratory accreditation program.

How can I find a lab to analyze my drinking water samples?

For homeowners considering testing to evaluate PFAS in their drinking water, EPA recommends contacting your state to learn if they have state certified laboratories to test for PFAS. For drinking water, EPA recommends using an EPA validated testing method.