PFAS Water Testing — EPA 533/537.1 vs 1633 by Matrix
PFAS water analysis starts with the matrix: drinking-water compliance uses EPA methods 533 or 537.1, while non-potable waters fall under Method 1633. The right method, a defined analyte list and rigorous field blanks matter more than the laboratory's headline detection limit.
Choose the method by matrix
Methods 533 and 537.1 are validated for drinking water and cover defined analyte lists. EPA's Method 1633, finalized in January 2024 with subsequent updates, covers wastewater, surface water, groundwater and other matrices with a 40-analyte list; verify the current version with EPA and the laboratory's accreditation or validation for that method and matrix. No single method quantifies every PFAS, and total-organic-fluorine approaches answer a different question.
Prevent sampling artefacts
PFAS-free containers, field reagent blanks and avoidance of fluorinated materials in sampling gear are standard requirements. Ask the laboratory to supply its sampling protocol and to state holding times and preservation. A detection in a sample without clean field blanks invites challenge.
Read the report critically
Confirm the analyte list, reporting limits, isotope-dilution quantitation and any qualifiers (estimated values, blank contamination). State the regulatory context in the RFQ so the laboratory applies the required method version and quality system. A 'non-detect' is only meaningful with the reporting limit stated.
Program-specific method selection
Drinking-water approval under applicable Part 141 provisions differs from Clean Water Act Part 136 and industry-specific requirements. SW-846 concerns solid-waste/RCRA analytical work and is not interchangeable approval. Specify jurisdiction, program, permit, matrix, analytes and reporting limits before choosing methods.
- Private request: matrix, analytes, reporting limits, jurisdiction and program/permit.
- Provider confirms actual preservation, holding times, containers and approved method edition before sampling.
Sample considerations
- State the matrix, the regulatory or investigation context and the required analyte list.
- Use laboratory-supplied containers and include field and equipment blanks.
- Agree reporting limits, turnaround-critical holding times and data deliverable format.
Questions to ask a laboratory
- Which method and version applies to our matrix, and what is your validated scope?
- What analytes and reporting limits will the report cover?
- How are blank contamination and estimated values flagged?
Laboratories with relevant capabilities
No directory profile currently documents this specific capability. Submit a request and we will look for laboratories that cover it.
Frequently asked questions
- Which method applies — EPA 537.1, 533 or 1633?
- In broad terms, EPA 537.1 and EPA 533 are drinking water methods with different analyte lists and chemistry, while EPA 1633 was developed for non-potable matrices such as wastewater, groundwater, soil, sediment, biosolids and tissue. The programme or permit driving your sampling normally names the method. If nothing names one, describe the water and the decision you need to make and let the laboratory advise.
- Do I need to know the method before submitting a request?
- No. Describe the water source, why you are testing and any regulatory or customer requirement you have been given. Laboratories select the method from that information.
- Can one water sample cover every PFAS compound?
- No single method covers all known PFAS. Methods have defined analyte lists, and compounds outside those lists — including many ultrashort-chain species — require a different approach.
- Why are field blanks emphasised so heavily?
- PFAS are used in many everyday materials, so contamination introduced during sampling is a leading cause of unusable data. Field and equipment blanks show whether a detection came from the water or from the sampling process.
Sources and scope references
EPA — PFAS analytical methods (incl. Method 1633)
Related testing briefs
Confirm standard edition, jurisdiction and actual laboratory scope. Service references are not partnerships or endorsements.