EPA Method 1633 / 1633A

Matrix

Non-potable/environmental: wastewater, surface water, groundwater, soil, biosolids, sediment, landfill leachate, and fish tissue

Analytes

40 PFAS analytes; uses isotopically labeled standards (isotope dilution/internal standard quantitation)

Status

Multi-laboratory validated across aqueous, solid, biosolids, and tissue matrices. Method 1633A finalized December 2024 (EPA 820-R-24-007) and proposed for approval at 40 CFR 136.3; NOT yet nationally required for CWA compliance monitoring until promulgated by rulemaking. EPA recommends it for non-drinking-water PFAS analysis.

Official source

https://www.epa.gov/cwa-methods/cwa-analytical-methods-and-polyfluorinated-alkyl-substances-pfas

When to use EPA Method 1633 / 1633A

Choose for environmental/non-potable matrices: wastewater (NPDES), groundwater/surface water, soil, sediment, biosolids/sewage sludge, landfill leachate, and fish tissue. The current single-method standard for multi-matrix environmental PFAS work.

Not sure this is the right method?

Pick the method by your matrix first, then by data-quality needs. DRINKING WATER (tap, well, finished/treated water): use EPA Method 537.1 (18 PFAS, includes GenX) and/or EPA Method 533 (25 PFAS, short-chain focus, isotope dilution). Together they cover 29 unique PFAS, and both are EPA-approved for compliance monitoring under the PFAS National Primary Drinking Water Regulation. For a home/well drinking-water test, a lab certified for 537.1 and/or 533 is what you want. Method 537 (the original 2009, 14 analytes) is mostly historical -- prefer 537.1. NON-POTABLE / ENVIRONMENTAL samples (wastewater, surface water, groundwater, soil, sediment, biosolids/sludge, landfill leachate, fish tissue): use EPA Method 1633/1633A (40 PFAS, isotope dilution, multi-matrix; finalized Dec 2024 and proposed for CWA approval but not yet nationally mandated). For aqueous-only environmental screening under RCRA/SW-846, Method 8327 (24 PFAS, external standard) exists but is generally superseded by 1633 for serious work. Quick rule: drinking water = 533 + 537.1; everything else (soil/sludge/wastewater/tissue) = 1633.

Compare all methods on the PFAS testing overview.

Find a lab accredited for EPA Method 1633 / 1633A

For DRINKING WATER PFAS testing, use a state-certified drinking-water laboratory: start at EPA's drinking-water lab certification page, which links to each state's certification program and lists of state-certified labs (EPA: 'Contact Information for Certification Programs and Certified Laboratories for Drinking Water'). Confirm the lab holds certification specifically for EPA Method 537.1 and/or 533 for the PFAS analytes you care about. For ENVIRONMENTAL/non-potable PFAS (soil, wastewater, biosolids, tissue), look for a lab accredited under TNI/NELAP for the relevant method (e.g., 1633, 8327) -- search the TNI LAMS (Laboratory Accreditation Management System) by lab name, state, accreditation body, and field of accreditation, and verify the specific PFAS analytes/method are listed in their scope. Always verify (1) the exact method, (2) the matrix, and (3) the specific analytes are on the lab's current accreditation/certification scope before sampling, since scopes change (e.g., many accreditation bodies added PFAS fields of accreditation effective Jan 1, 2025).

• TNI LAMS - National Environmental Laboratory Accreditation Management System (search for NELAP-accredited labs by name, state, accreditation body, and field of accreditation, including PFAS), National searchable database of TNI/NELAP-accredited environmental laboratories; filter for PFAS methods/analytes and matrices.
• NELAP Accreditation Bodies - The NELAC Institute (TNI), List of state and third-party NELAP accreditation bodies; useful for verifying a lab's accrediting authority and scope.
• EPA - Contact Information for Certification Programs and Certified Laboratories for Drinking Water, EPA hub linking to each state's drinking-water lab certification program and its list of state-certified drinking-water labs (use to find labs certified for Methods 537.1/533).