PFAS well testing: which labs actually have Method 533 / 537.1 on scope

WellTestList · Thursday, September 3, 2026 · PFAS methods

“We test for forever chemicals” is not a method. For drinking water, the EPA pair that matters is Method 537.1 and Method 533. A lab can be certified for coliform and still have zero PFAS methods on its certificate. This page is how to ask the right question, verify the answer, and get a PDF — not a sales visit.

The short version

Ask for Method 533, Method 537.1, or both — by number. Together they cover 29 PFAS in drinking water. EPA’s methods page (updated April 24, 2026) says both are approved for UCMR 5 monitoring and for the PFAS National Primary Drinking Water Regulation. “Modified 537” is not the same thing.
Verify the lab’s current scope before you pay. Certification is by method, matrix, and analyte — not a vibe. Use your state’s drinking-water lab certification program, or search TNI LAMS for 533 or 537.1. Then call: many certified labs only serve utilities.
Private wells are not under the federal utility rule. The April 2024 rule set enforceable MCLs of 4.0 ppt for PFOA and PFOS for public systems. Those numbers are still the useful health benchmark on a homeowner report. They do not force your well to be tested. You are still the utility.

533 vs 537.1 vs 1633 (what each is for)

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Drinking-water method sketch checked September 3, 2026 against EPA’s PFAS laboratory-methods page and product pages that name a method. Analyte counts for 537.1 / 533 are the common published panel sizes (18 and 25). Combined, EPA says the two methods measure 29 PFAS.
Method	What it is	Typical panel	When to ask for it
EPA 537.1	Drinking-water SPE + LC/MS/MS. Ver. 2.0 (2020) superseded Method 537 for most uses.	~18 PFAS, including PFOA and PFOS	Baseline forever-chemical panel on finished drinking water / well water treated as potable.
EPA 533	Drinking-water method with isotope dilution; stronger on short-chain PFAS.	~25 PFAS, including GenX (HFPO-DA), PFOA, PFOS	When you want the broader EPA drinking-water pair, or GenX / short-chain coverage.
EPA 533 + 537.1	The approved NPDWR / UCMR 5 drinking-water pair.	Up to 29 PFAS combined	When a regulator, attorney, or investigation desk named “the EPA drinking-water methods.”
EPA 1633	Broader PFAS method family used across more matrices (wastewater, solids, etc.). Not the NPDWR drinking-water pair.	Wider compound lists (kits may advertise ~40)	Near a known source when you want a wider screen — still ask what accreditation the lab holds for your sample type.
“Modified 537” / strip / free kit	Not EPA-approved for UCMR 5 or the PFAS drinking-water rule. Strips are screening-only.	Varies; often not quantified to ppt the way a certified method is	Do not use as the health decision or the lender file. See the Home Depot free-kit page.

EPA’s own FAQ: techniques other than 533 and 537.1 may be fine for some research goals, but they have not been evaluated by EPA for UCMR 5 or NPDWR compliance. If someone says “modified,” ask what was modified and whether your state certifies that version for drinking water.

How to verify a lab actually has the method on scope

Start with your state laboratory certification program. EPA’s national page still points homeowners and utilities to the state certification contact list. Ask for labs certified for drinking-water PFAS by Method 533 and/or 537.1.
Or search TNI LAMS. The National Environmental Laboratory Accreditation Management System search is at lams.nelac-institute.org/Search. Put 533 or 537.1 in the method filter (ASDWA’s PFAS lab-testing primer walks the same path). Accreditation is per method / matrix / analyte — open the lab’s scope, do not stop at the name.
Use a state PFAS PDF when one exists. Michigan publishes separate in-state and out-of-state PFAS lab lists. Other states are building the same thing for the federal rule. We are not inventing a 50-state phone book tonight.
Then call before you collect. Ask, in this order: Do you accept a residential / private-well sample? Which method(s) — 533, 537.1, or both — are on your current certificate for drinking water? What bottles and field blank do you require? Price? Hold / ship rules? Do you email a PDF? Certification for utilities does not mean they take a homeowner bottle.

Mail-in kits that name a real method (checked tonight)

We affiliate only independent mail-in labs that email a PDF. Tonight’s listed Tap Score / SimpleLab PFAS kits (Shopify / product pages, September 3, 2026):

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Listed prices September 3, 2026. Not a coupon. Kits change — read the product page before you pay.
Kit	Listed price	Method named	Lab turnaround (listed)
Tap Score PFAS Water Test	$335	EPA 537.1 · 18 analytes	~10 business days at lab; standard shipping included
Tap Score GenX and PFAS	$599	EPA 533 · 25 analytes	~12 business days; their recommended PFAS kit
Tap Score EPA 1633 PFAS	$835	EPA 1633 · 40 analytes	~15 business days; wider screen, not the NPDWR pair
Tap Score Extended Well	$1,125 (Aug 30 check)	142 analytes including 25 PFAS	Broader well panel with PFAS folded in — see the cost table

National Testing Labs / Watercheck Basic, Standard, and Deluxe kits on the well-water collection tonight do not list a Method 533 or 537.1 PFAS panel. Do not treat a Watercheck Deluxe as a forever-chemical file. If you want NTL specifically, call them and ask whether they offer a custom PFAS method — we will not invent a SKU we did not see.

Michigan homeowners who want to stay in-state: EGLE’s published fee for its own PFAS test (CXPFAS) was $290 on the schedule we already cited on the Michigan page. Call 517-335-8184 before you collect; codes change. MDHHS may test some investigation-area homes for free.

When PFAS testing is worth the money

You live near a military base, airport, or fire-training site that used aqueous film-forming foam (AFFF).
There is a known industrial PFAS source, landfill, or state investigation near your well.
Your public-supply neighbors posted detections and you are on a private well in the same aquifer / neighborhood.
A realtor, attorney, or county health desk asked for a Method 533 / 537.1 report by name.
You already did bacteria and nitrate and still want a one-time forever-chemical baseline.

Minnesota’s health department, for example, does not tell every private-well owner to buy a PFAS kit by default — see our Minnesota page. Match the panel to the land. Annual bacteria and nitrate still come first for most wells.

Sampling is fussier than a bacteria bottle

PFAS sticks to ordinary plastics and rides on hands, jackets, and field gear. Kits that run 533 / 537.1 ship special bottles and usually a field reagent blank. Follow the kit sheet exactly. Do not invent a DIY protocol from a blog. If the lab rejects the blank or the bottle, that is the method working — not a conspiracy. Collect when you can ship the same day the lab named; this is not a Friday mailbox errand (see hold-time notes on the flood page for the general clock problem).

What to do tonight

Decide why you need PFAS (nearby source, investigation, or one-time baseline). If you only need the yearly coliform, call county health first — see the cost table.
Pick a path that names a method: state-certified drop-off with 533 / 537.1 on the current certificate, EGLE’s CXPFAS if you are in Michigan, or a Tap Score kit that prints EPA 537.1 or 533 on the product page.
Verify scope in writing (state list, LAMS, or the kit’s accredited-lab network) and ask for a PDF. Ask whether they accept private-well samples.
Skip strips, free in-store kits, and anyone who wants both spouses home to “go over results.” That is lead-gen. We refuse it.

Not this if…

The salesperson said “we test for PFAS” without naming 533 or 537.1. Ask for the method number and the lab’s certificate. No number, no sale.
You bought an aisle strip or an immunoassay kit. Screening-only. Not a certified drinking-water method.
You assumed Watercheck Deluxe or a generic “well panel” includes forever chemicals. Tonight’s NTL well kits did not list 533 / 537.1. Tap Score Essential / Advanced well panels also keep full PFAS as a separate (or Extended) SKU.
You needed a lender chain-of-custody file. A health PDF and a closing file are not always the same SKU — see the home purchase / lender page.
Someone offered a free post-detection “whole-house treatment test.” Get the lab PDF first. Treatment is a later decision, after numbers.

Sources checked September 3, 2026: EPA PFAS drinking-water laboratory methods (page updated April 24, 2026); April 2024 PFAS NPDWR (PFOA/PFOS MCL 4.0 ppt each for public systems); ASDWA PFAS Laboratory Testing Primer (NELAP / LAMS path); TNI LAMS search; Tap Score product pages / Shopify JSON for PFAS, GenX+PFAS, and EPA 1633 kits; NTL Watercheck well-water collection (no 533/537.1 SKU listed tonight); EGLE Michigan PFAS lab PDFs and CXPFAS fee already cited on our Michigan page. Federal proposal activity around compliance deadlines and other PFAS MCLs was in motion in 2026 — we quote the published 4.0 ppt PFOA/PFOS MCLs as benchmarks and do not treat proposals as final law. Affiliate disclosure: links to Tap Score / SimpleLab may earn WellTestList a commission (rel="sponsored nofollow"). National Testing Labs links are not affiliate links; we earn nothing from them. That does not change who we refuse to list.