PFAS in well water

Best for

Homes near airports, military bases, firefighting training areas, industrial sites or landfills, and anyone who wants to know before choosing treatment.

Wrong fit

If you already have a recent PFAS result from a state investigation, skip ahead to treatment and work with your state agency on it.

Tradeoff

PFAS samples must be collected carefully, results are in parts per trillion, and current filter certifications do not yet prove removal down to the EPA limits.

What PFAS are

PFAS (per- and polyfluoroalkyl substances) are a large family of man-made chemicals used for decades in firefighting foam, non-stick cookware, food packaging and industrial processes. The Minnesota Department of Health notes they are extremely stable and do not break down in the environment, which is why they are called “forever chemicals.” You cannot see, taste or smell them.

Are private wells affected?

Yes, about as often as city water. A USGS study tested tap water at 716 locations from 2016 to 2021, including private wells, and estimated that at least 45% of the nation’s tap water has one or more PFAS. It found PFAS concentrations similar between public supplies and private wells. The USGS tested for 32 PFAS; there are more than 12,000 types, and not all can be detected with current tests.

Location matters. The USGS saw the most exposure near urban areas and known PFAS sources such as industry and waste sites, and estimated the probability of no PFAS being found in tap water at about 75% in rural areas and about 25% in urban areas. Wells at higher risk include those near:

• Airports, military bases and fire training areas where firefighting foam was used.
• Factories that made or used PFAS.
• Landfills and waste disposal sites.

Some states investigate known contamination sites and sample nearby private wells. In Minnesota, for example, the state pollution agency notifies owners whose wells may be affected and samples wells in its investigations. Check your state’s program under states before paying for a test.

Is it a health risk?

Minnesota summarizes the research: higher PFAS exposure has been associated with higher cholesterol, changes in liver function, reduced immune response, thyroid disease and, for PFOA, increased kidney and testicular cancer. It also notes that more work is needed to confirm cause and effect. The EPA has set health goals of zero for PFOA and PFOS.

Infants are a particular concern. Minnesota advises preparing infant formula with filtered tap water or bottled water if your private well has not been tested for PFAS.

The EPA limits, as of November 2026

In April 2024 the EPA finalized drinking water limits for six PFAS. They apply to public water systems, not private wells, but they are the best yardstick for a well result:

A proposal is not a final rule, and EPA’s stated reason for the rescission proposal is procedural, not a new finding that these chemicals are safe. For a private well, it is reasonable to treat any of these above their 2024 levels as a reason to act, and to ask your state health department what it recommends.

Note the units. 4.0 ppt is 4.0 nanograms per liter, a thousand times smaller than the µg/L units used for arsenic. Some labs report PFAS in ng/L, others in ppt; they are the same.

How to test

Use a state-accredited laboratory that analyzes PFAS in drinking water. Minnesota tells well owners to contact the lab directly about the number of samples, collection and shipping. PFAS are in many everyday products, so follow the lab’s instructions closely to avoid contaminating the sample.

A good PFAS test reports a list of individual compounds with a reporting limit for each. Make sure it includes at least PFOA, PFOS, PFHxS, PFNA, GenX and PFBS so you can compare against the table above. A certified-lab mail-in test such as Tap Score’s well water tests is one option; confirm the package you choose includes PFAS before you order. The guides to testing your well and well water test kits explain what to ask for, and the test results tool builds a plan from your numbers.

If your result is X, do Y

Treatment options

The EPA says granular activated carbon, ion exchange and reverse osmosis point-of-use systems studied can greatly reduce PFAS levels. Minnesota’s home treatment guide lists reverse osmosis among the technologies that remove PFAS and notes an MDH study found GAC filters effective.

Certification. The EPA advises looking for certification under NSF/ANSI 53 or NSF/ANSI 58 for PFAS reduction, checking which PFAS a product is certified for in NSF’s listings, and confirming with the manufacturer. The EPA also cautions that certification standards, as of April 2024, did not yet show that a filter removes PFAS down to the new EPA limits. Maintenance matters too: the EPA says filters only work if they are replaced on the manufacturer’s schedule.

Well water pretreatment. NDSU Extension notes that sediment clogs activated carbon quickly and recommends a sediment filter ahead of any carbon unit. If your well also has iron, manganese or hardness, those are usually treated upstream of a PFAS system.

SpringWell sells a whole-home PFAS Water Filter System. Its product page says it reduces PFAS to non-detect levels below 1 ng/L at every tap, and lists a 7 GPM flow rate for 1 to 5 bathrooms with replaceable cartridges. The product page does not name a specific certification, so check NSF’s listings for the exact model and the specific PFAS it covers before relying on it. For most well owners, the order is the same: test first, then size treatment to the result. The reverse osmosis guide covers the most common point-of-use option.

Maintenance and retesting

• Replace carbon, resin cartridges and RO membranes on the maker’s schedule. PFAS give no warning when a filter is exhausted.
• Test the treated water after installation, and periodically after that, to confirm the filter is working.
• Keep a copy of your results; they are useful if a state investigation later reaches your area.

When to call the health department

Call your state health department or environmental agency if PFOA or PFOS is at or above 4.0 ppt, if you live near a known PFAS site, or if you are pregnant or have an infant. They can explain current guidance and may know about state testing or treatment assistance programs.