PFAS in well water: should you test, and what removes them?

PFAS (per- and polyfluoroalkyl substances) are manufactured chemicals that have been used in industry and consumer products since the 1940s². They are extremely stable and do not break down in the environment⁴, which is how they end up in groundwater decades after they were used.

For a well owner the starting point is this: EPA does not regulate private wells or provide recommended standards for them². If your water comes from your own well, nobody is testing it for PFAS, and deciding whether to test is up to you.

Is your well likely to be affected?

For most wells the risk is low. Penn State Extension says PFAS in groundwater are more common near places where they were used or disposed of⁵:

• military bases and fire training centers
• manufacturing plants
• dumps and landfills
• fields where contaminated biosolids were spread

EPA’s list of possible sources adds fire extinguishing foam, waste sites and manufacturing waste².

Minnesota’s health department does not recommend that every private well be tested for PFAS⁴. A sensible first step is the one EPA suggests: contact your state environmental or health agency for advice and for a list of certified laboratories².

What PFAS do

The research is still developing, and the agencies choose their words carefully.

• Minnesota says higher exposure is associated with higher cholesterol, changes in liver function, reduced immune response and thyroid disease, and, for PFOA specifically, kidney and testicular cancer. It adds that more research is needed to confirm whether PFAS or other factors cause these effects⁴.
• EPA says that water above the federal standard does not necessarily mean health effects will occur. The risk depends on the level, on how much and how long a person is exposed, and on the individual².

The numbers, and where they stand

In 2024 EPA set the first federal limits for PFAS in public drinking water¹:

Compound	Limit	Health goal
PFOA	4.0 ppt	Zero
PFOS	4.0 ppt	Zero
PFHxS	10 ppt	10 ppt
PFNA	10 ppt	10 ppt
HFPO-DA (“GenX”)	10 ppt	10 ppt

Source: EPA. One part per trillion (ppt) is one nanogram per liter. These limits do not apply to private wells.

These are changing. On May 18, 2026, EPA announced two proposals: one keeps the limits for PFOA and PFOS and lets water systems ask for two more years, to 2031, to comply, and the other would withdraw the limits for PFHxS, PFNA and HFPO-DA¹. Whatever happens to the proposals, the 4.0 ppt figures for PFOA and PFOS are the ones to compare a well result with.

Two more things to know when reading a result:

• The units are tiny. A part per trillion is a nanogram per liter. A report in micrograms per liter will show 4 ppt as 0.004 µg/L.
• States differ. Pennsylvania, for example, set its own limits of 14 ppt for PFOA and 18 ppt for PFOS⁵. In Canada, Health Canada’s objective is 30 ng/L for the sum of 25 PFAS⁶.

How to test

1. Use a state-certified laboratory that runs EPA’s drinking water methods². There are two: Method 537.1 measures 18 PFAS compounds and Method 533 measures 25⁵.
2. Budget for it. Penn State puts the cost at around $250 to $500 per sample⁵.
3. Follow the kit instructions exactly. Labs usually send bottles with method-specific instructions for collecting, handling and shipping⁵.

If PFAS are found

EPA’s advice for a well with PFAS²:

• Consider another source of water for drinking, cooking, brushing teeth, preparing baby formula and anything else where water is swallowed.
• Consider a treatment system or filter certified to lower PFAS.
• Keep testing the well.

Call your state agency with the results. Minnesota, for example, has staff who help well owners interpret them⁴.

Filters that reduce PFAS

EPA found that three kinds of filter can greatly reduce PFAS when they are properly maintained³:

Type	Certification to look for	Typical cost	Notes
Granular activated carbon	NSF/ANSI 53 for PFAS reduction	$20 to $1,000
Ion exchange resin	NSF/ANSI 53 for PFAS reduction	$20 to $1,000
Reverse osmosis	NSF/ANSI 58	$150 to $1,000	Wastes about a gallon for every gallon treated

Costs are EPA's estimates and do not include maintenance.

Types, certifications and costs are EPA’s³. Penn State describes the two ways to install them: at one tap, which avoids most exposure because most of it comes from the water you drink, or for the whole house⁵.

Two habits matter more than the brand:

• Change cartridges and membranes on schedule. A filter only works if it is maintained, and EPA warns that a missed replacement can increase your exposure²³.
• Check the claim. Look for the standard on the packaging, then confirm it in the certifier’s listings. EPA names CSA Group, IAPMO, NSF, UL and WQA³.

Who pays

Usually you do. If the PFAS come from a Superfund site, EPA may provide a temporary alternative source of drinking water; if they come from somewhere else, the law does not allow Superfund money to be used². EPA also says federal infrastructure funding is available to help owners of private wells address PFAS¹. Your state agency is the place to ask what applies to you.

Keep the basics going

PFAS get the headlines, but the yearly tests for bacteria and nitrate are the ones every well needs. See what to test well water for, and our guides to lead and arsenic.