Testing well water for PFAS: what you need to know before you order a kit

Updated February 2026

Your standard well water test doesn’t check for PFAS. Not the county health department test, not the basic mail-in kit, not the strips from the hardware store. PFAS require specialized lab equipment, specific EPA-approved methods, and samples handled under strict protocols. If you haven’t ordered a dedicated PFAS test, you have no idea whether your well water contains forever chemicals.

That’s the part that caught me off guard. I’d been testing my well annually for bacteria, nitrates, pH, hardness — the usual panel. I assumed that if something dangerous was in my water, those tests would catch it. They didn’t. PFAS could have been sitting in my water for years at levels that the EPA now considers unsafe, and I’d have had no way of knowing.

Here’s what I’ve learned about testing for PFAS, which kits are worth the money, and how to read the results once you get them back.

Why regular well water tests miss PFAS completely

The reason is technical but straightforward. PFAS — per- and polyfluoroalkyl substances — are measured in parts per trillion. That’s three orders of magnitude smaller than the parts per billion used for most other contaminants. Detecting something at 4 parts per trillion requires liquid chromatography-tandem mass spectrometry (LC-MS/MS), which is not the kind of equipment sitting in a county lab or packed into a $30 test strip.

To put 4 parts per trillion in perspective: one part per trillion is one drop of water in 20 Olympic swimming pools. The EPA’s limit for PFOA and PFOS — 4 ppt — is four drops spread across those same 80 pools. The fact that we can even measure at this scale is a relatively recent analytical achievement. It’s why PFAS testing requires dedicated certified labs and why it costs more than a standard water panel.

Standard water tests check for bacteria, nitrates, pH, hardness, iron, manganese, and maybe a handful of volatile organic compounds. Good tests. Important tests. But they don’t even attempt PFAS detection because the methodology is completely different.

EPA Method 537.1 and EPA Method 533 are the two primary certified analytical methods for PFAS in drinking water. Method 537.1 targets 18 PFAS compounds including PFOA and PFOS (the two most studied). Method 533 covers 25 compounds and picks up shorter-chain PFAS that 537.1 misses. The newer draft Method 1633 casts an even wider net at 40 compounds. When you order a PFAS test, make sure the lab is using one of these certified methods — not a proprietary screening approach.

The upshot: you need a separate test, from a certified lab, using one of these specific methods. No shortcuts.

The 2024 federal PFAS standards: what changed and why it matters for well owners

In April 2024, the EPA finalized the first-ever national, legally enforceable drinking water limits for PFAS — the Maximum Contaminant Levels (MCLs). This was a significant milestone: for the first time, there are federal standards with actual teeth.

Here’s what was set:

Compound	MCL
PFOA	4 ppt
PFOS	4 ppt
PFHxS	10 ppt (Hazard Index)
PFNA	10 ppt (Hazard Index)
HFPO-DA (GenX)	10 ppt (Hazard Index)

The “Hazard Index” approach for PFHxS, PFNA, and GenX means the EPA looks at these three compounds together as a mixture, not just individually. If the combined health risk of the three exceeds the threshold, that’s a violation — even if each one individually is under 10 ppt.

The critical caveat for well owners: These MCLs apply to public water systems — community water supplies serving 25 or more people. They do not legally apply to private wells.

That doesn’t make them irrelevant to you. It makes them the best benchmark available. When the federal government’s toxicologists set an enforceable limit at 4 ppt for PFOA and PFOS, that number is based on decades of epidemiological data on health outcomes — cancers, thyroid disruption, immune effects. The science doesn’t change based on whether your water comes from a municipal system or a private well. If your well tests above 4 ppt PFOA, that’s meaningful information regardless of the regulatory jurisdiction.

Use the MCLs as your reference line. They’re not a guarantee of safety below 4 ppt — health researchers continue to debate whether any detectable level is truly safe — but they’re the most current, evidence-based threshold we have.

Should you test? How to assess your risk

Not every well owner needs to rush out and order a PFAS kit tomorrow. But some should have tested yesterday. Here’s how to figure out where you fall.

Test now if any of these apply:

You live within 10 miles of a current or former military base. The Department of Defense has identified 723 installations with known or suspected PFAS releases, primarily from decades of using PFAS-based firefighting foam (AFFF) during training exercises. At 630 of those sites, lab tests have confirmed PFAS in groundwater.
You live near an airport, especially one with fire training facilities.
You live near an industrial facility that manufactures or uses PFAS — this includes textile manufacturing, semiconductor plants, chrome plating operations, and certain paper mills.
You live near a wastewater treatment plant that accepts industrial discharge, or near where biosolids (treated sewage sludge) have been applied to farmland.
Your state has flagged your county or region as a PFAS concern area. Several states (Maine, Michigan, New Hampshire, New Jersey, North Carolina) have been particularly proactive about mapping contamination.

Test when you can if none of those apply. A 2023 USGS study sampled tap water from 716 locations across the US and detected PFAS in 20% of private wells tested. A follow-up study in 2024 estimated that 71 to 95 million people in the lower 48 states may rely on groundwater containing detectable PFAS. The contamination is more widespread than the “near a military base” framing suggests. PFAS are in firefighting foam, but they’re also in Teflon manufacturing waste, food packaging, stain-resistant carpet treatments, and hundreds of other industrial processes. The chemicals are mobile in groundwater and persistent — they don’t break down.

If you’re a well owner and you’ve never tested, $80 to $300 buys peace of mind or actionable data. Either way, you’re better off knowing.

Subsidized and free testing for private well owners

Before you spend anything, check whether your state offers subsidized or free PFAS testing for private wells. Several states have active programs specifically targeting high-risk areas near military bases, airports, and industrial facilities:

Maine has tested thousands of private wells statewide and offers free testing through the Maine CDC.
Michigan provides free PFAS testing for private wells in areas near known contamination sites.
New Hampshire runs a targeted well testing program in communities near contamination sources.
Colorado’s PFAS TAP program partners with Cyclopure to provide free testing in targeted counties.
North Carolina has ongoing testing programs near the Fayetteville Works facility.

Your state’s environmental or health department website is the place to check. Search “[your state] PFAS private well testing program.” These programs tend to be limited geographically, but if you’re in a qualifying area, the testing is free and uses the same certified methods as the paid kits — EPA Method 533 or 537.1 run by accredited state labs.

The three PFAS test kits worth considering

I’ve dug into the major options. Here’s what I’d recommend depending on your budget and how thorough you want to be.

Cyclopure Water Test Kit — $79

This is the entry point, and it’s surprisingly good for the price. Cyclopure tests for 55 PFAS compounds, which is more than either EPA Method 537.1 or 533 alone. Their kit uses a different approach than traditional mail-in kits: instead of shipping a water sample to a lab, you pour water through a small extraction disc that captures the PFAS on-site. Then you mail the disc.

The collection process takes about 20 minutes (slower than filling a vial, but not difficult). Results come back in 10 to 14 business days. The report is clear and covers the compounds that matter, though it’s not as interactive as Tap Score’s dashboard.

At $79, this is what I’d recommend for most well owners doing an initial screen. The compound coverage is actually broader than kits costing three or four times as much.

Tap Score PFAS Test — $299

Tap Score (made by SimpleLab) is the kit recommended by the New York Times Wirecutter and it’s the one I’d pick if you want the most polished experience. Their standard PFAS test covers 14 compounds using EPA Method 537.1. You collect a water sample in their provided container, ship it with the prepaid label, and get results in about 10 to 15 business days.

What sets Tap Score apart is the results dashboard. Instead of a static PDF, you get an interactive report that flags exceedances against the EPA’s 4 ppt MCL for PFOA and PFOS. It highlights which compounds were detected, how your levels compare to regulatory thresholds, and what treatment options apply. For someone who’s never read a lab report, this is a big deal.

If you want broader compound coverage from Tap Score, their GenX + PFAS test ($579) covers 25 compounds under EPA Method 533, and their EPA 1633 test covers 40 compounds.

How to collect the sample correctly

PFAS testing is finicky about contamination. The testing labs send specific containers for a reason — PFAS are in so many consumer products that you can accidentally introduce them into your sample.

A few things to keep in mind:

Don’t use any containers other than the ones provided in the kit. Many plastics contain PFAS or release compounds that interfere with the analysis.
Wash your hands with PFAS-free soap before collecting. Most waterproof cosmetics, sunscreen, and many hand lotions contain PFAS. If any of that transfers to the sample container, it can skew results.
Remove any faucet aerators or filters before collecting. You want raw well water, not filtered water.
Run the tap for 2 to 3 minutes before collecting to flush standing water from the pipes. You want a sample that represents your actual groundwater, not water that’s been sitting in copper pipes overnight.
Don’t wear Gore-Tex, Scotchgard-treated clothing, or other water-resistant fabrics while collecting. They shed PFAS.

These protocols sound extreme, but when you’re measuring in parts per trillion, a thumbprint of sunscreen residue on the sample vial could produce a false positive.

Reading your results: what the numbers actually mean

Your report will list individual PFAS compounds with concentrations in parts per trillion (ppt) or nanograms per liter (ng/L) — these are the same unit. Here’s how to interpret them.

The EPA’s enforceable limits (as of April 2024):

Compound	Maximum Contaminant Level (MCL)
PFOA	4 ppt
PFOS	4 ppt
PFHxS	10 ppt (Hazard Index with PFNA and GenX)
PFNA	10 ppt (Hazard Index with PFHxS and GenX)
HFPO-DA (GenX)	10 ppt (Hazard Index with PFHxS and PFNA)

These standards apply to public water systems; private wells are not subject to federal MCL enforcement. But they are the most rigorously derived safety benchmarks available, and they should be your reference point.

What “non-detect” means. If your results say “ND” or “non-detect” for a compound, it means the concentration was below the lab’s limit of quantification (LOQ). For most certified labs using Method 533 or 537.1, that’s around 1 to 2 ppt. Non-detect is good news, but it doesn’t mean zero — it means below the level the equipment can reliably measure.

What to do if PFOA or PFOS exceed 4 ppt. This is the threshold where you need to take action. The options are:

Install a treatment system. Reverse osmosis is the most effective residential technology for PFAS removal, reducing levels by 94% or more across a wide range of PFAS compounds including shorter-chain varieties. Activated carbon filters (granular or block) also work, particularly for longer-chain PFAS like PFOA and PFOS, though performance varies more. Look for systems certified to NSF/ANSI 53 (carbon filters) or NSF/ANSI 58 (reverse osmosis). More on this in the filtration guide.
Switch to bottled water for drinking and cooking as an immediate interim step while you evaluate treatment options.
Retest in 6 months to confirm the results if levels are close to the threshold (say, 3 to 6 ppt). PFAS concentrations in groundwater can fluctuate seasonally.

What to do if compounds are detected but below 4 ppt. You’re technically within the EPA’s current framework, but this isn’t a “pass” in the traditional sense. PFAS are bioaccumulative — they build up in your body over time. Some health researchers argue that any detectable level warrants attention, especially for pregnant women, nursing mothers, and young children. At minimum, retest annually to track whether levels are rising.

The health picture: why these chemicals matter

PFAS are called “forever chemicals” because they don’t break down in the environment or in your body. They accumulate in blood and organs over years of exposure.

The health research has grown substantially. Epidemiological studies have linked PFAS exposure to increased risk of kidney and testicular cancers, thyroid disruption, elevated cholesterol, reduced immune response (including weaker vaccine effectiveness in children), pregnancy complications, and liver damage.

A study published in the Journal of Exposure Science & Environmental Epidemiology estimated that PFAS contamination in US drinking water contributes to roughly 6,800 cancer cases per year.

These are population-level associations, not guarantees of individual harm. But unlike a lot of environmental health research where the evidence is murky, the PFAS data is getting more definitive with each study. The federal government doesn’t set enforceable MCLs at 4 parts per trillion unless the evidence is strong.

How often to retest

If your initial results come back clean (non-detect across the board), retest every 3 to 5 years unless conditions change. “Conditions change” means new industrial activity near your property, new construction that disturbs contaminated soil, or new reports of PFAS contamination in your area.

If your results show detectable PFAS below the MCL, retest annually. You’re tracking a trend line, not just a snapshot. If levels are stable or declining, you can extend the interval. If they’re creeping up, it’s time to install treatment before they cross the threshold.

If you install a treatment system, test both your raw well water and the treated water annually. The raw water test confirms whether the contamination source is stable or worsening. The treated water test confirms your filter is actually working. Carbon filters in particular lose effectiveness as the media becomes saturated, and there’s no way to tell when that happens without testing.

Already dealing with water quality issues? If your well water has other problems — iron staining, sulfur smell, bacteria, sediment — the well water filtration guide walks through how to build a treatment system that handles multiple contaminants. PFAS treatment works best as the last stage in a multi-stage setup, after sediment and iron have been removed upstream.

Your next step

Pick the test that fits your budget. If money is tight, Cyclopure at $79 gives you the broadest compound coverage per dollar. If you want the best results experience, Tap Score at $299 has the clearest reporting. Either way, check your state’s free testing programs first — you might not need to pay anything.

Order the kit, follow the collection instructions to the letter, and mail it back. In two weeks, you’ll know whether PFAS is a problem in your well or one less thing to worry about.