How to Test Water for PFAS and Read the Result

A PFAS water test needs a laboratory analysis, because a simple home strip cannot give a dependable result for per- and polyfluoroalkyl substances (PFAS). The Environmental Protection Agency (EPA) lists drinking water methods for PFAS that include Methods 533 and 537.1, and both use liquid chromatography with tandem mass spectrometry. EPA's limits are stated in nanograms per liter (ng/L), and one nanogram per liter equals one part per trillion (ppt).

At The Indoor Report, we compile and explain the published standards for PFAS testing. Who needs a test depends on where the water comes from, and the first section starts there.

EPA announced national drinking water standards for PFAS in April 2024, and EPA has since announced changes to parts of that rule. Verify the current limits and compliance dates on the EPA PFAS page before you rely on any figure here.

Who Should Test for PFAS

Private well owners carry the PFAS testing responsibility, and EPA's limits do not cover private wells. Testing a private well is the owner's decision and responsibility.

EPA says state or local health departments can usually say whether PFAS have been found near a given area, so ask yours before you order a lab test. EPA says PFAS can reach drinking water from industrial sites, airports and military bases where firefighting foam was used, and from landfills. For the private well side in general, see well water testing.

Public water customers can start with the utility's own PFAS results. If you get water from a public system, start with the utility's own PFAS results, covered in a later section, before you order a private lab test. A private lab order is not your first step in that case.

Why a Laboratory Analysis Is the Dependable Route

A laboratory analysis is the dependable route for a PFAS result, because a simple home strip cannot check for these compounds reliably. EPA's drinking water methods for PFAS include Method 533 and Method 537.1, and both use liquid chromatography with tandem mass spectrometry. Ask the lab which of these methods it uses before you send a sample.

Labs supply their own sample containers and sampling instructions for PFAS. Ask for both the containers and the steps before you collect any water.

Sampling Mistakes That Contaminate a PFAS Sample

Contamination from sampling materials is a known risk in PFAS sampling, so the lab's instructions set the procedure.

Use only the containers the laboratory supplies, and follow its sampling instructions exactly. Do not substitute a bottle or a step from another source, because the risk EPA names comes from the sampling materials themselves.

Nanograms per Liter and Parts per Trillion Mean the Same Thing

One nanogram per liter (ng/L) equals one part per trillion (ppt), so lab results and EPA's limits sit on the same scale. EPA's April 2024 standards set 4.0 ng/L for PFOA and PFOS. They set 10 ng/L for PFHxS, PFNA and HFPO-DA (GenX).

The table gives each figure in both units.

What EPA's Limits Cover and What They Do Not

EPA's drinking water limits apply to public water systems, and private wells are not covered by EPA rules.

EPA also sets a hazard index for mixtures.

EPA's fifth Unregulated Contaminant Monitoring Rule (UCMR 5) required public water systems to sample for 29 PFAS between 2023 and 2025, and EPA publishes the results. EPA has announced changes to parts of the 2024 rule, so the current limits and compliance dates should be verified. The advice on comparing results would change if EPA revises the limits again.

Public Water Customers Start with the Utility Report

Public water utilities publish an annual consumer confidence report, and PFAS results can appear in it or on the utility's website. Read the PFAS section before you order a lab test. For help with the units, see how to read a water report.

A utility report describes water from the public system. A utility report covers the public system, not a private well.

Home Test Kits Cannot Give a Reliable PFAS Answer

A home test kit cannot give a reliable PFAS answer, so a kit result alone should not settle the question. The EPA methods named for PFAS are laboratory methods, and check each kit's own detection range and accuracy before relying on it.

A negative kit result does not settle the question either, because the reliable answer comes from a laboratory analysis. For general kit options, see water test kit.

What to Do with a PFAS Result

A result above EPA's figures is a reason to contact your state or local health department, which can usually say whether PFAS have been found near your area. Read the full lab report before you choose any treatment.

The PFAS water filter page covers filter options at a general level. What reverse osmosis removes explains one treatment method. Check each filter's own specification for which PFAS it removes.

Health effects are not covered here, so a clinician is the right contact for questions about exposure.

Choosing an Accredited Lab for a PFAS Water Test

Many states certify or accredit drinking water laboratories, and your state drinking water program can supply a list of them. Compare the labs on three points.

Get any lab price from the lab itself. If you have a private well, ask your state drinking water program for its list of certified laboratories, then order a PFAS water test that uses an EPA drinking water method.

• Whether the laboratory holds state certification or accreditation for drinking water testing.
• Which EPA drinking water method, such as Method 533 or Method 537.1, the laboratory uses for PFAS.
• Whether the laboratory supplies its own PFAS sample containers and sampling instructions.