PFAS in Well Water: Testing, Levels & Treatment Options

Updated March 2026 · 13 min read · Reviewed by a certified water specialist

PFASPFAS (Per- and Polyfluoroalkyl Substances)Synthetic chemicals used in nonstick coatings, firefighting foam, and food packaging. Known as 'forever chemicals' because they do not break down in the environment.EPA MCL (2024): 4 ppt for PFOA and PFOS individuallyLearn more → (per- and polyfluoroalkyl substances) are called "forever chemicals." They do not break down in the environment — or in your body.

In 2024, the EPA set the first enforceable limits for PFAS in drinking water[1]. A 2023 USGS study found detectable PFAS in 45% of U.S. tap water[2]. Private wells are not tested or regulated. You are on your own.

Quick Answer

The EPA MCLMCL (Maximum Contaminant Level)The highest level of a contaminant allowed in public drinking water, set by the EPA. Private wells are not regulated by MCLs, but they serve as the best available safety benchmarks.Learn more → (maximum contaminant level) for PFOA and PFOS is 4 ppt (parts per trillion) each[1]. A reverse osmosisReverse Osmosis (RO)A treatment method that forces water through a semipermeable membrane, removing up to 99% of dissolved contaminants including arsenic, lead, fluoride, nitrates, and PFAS.Learn more → (RO) system under your sink removes 90–99% of PFAS for $200–$600. A whole-house granular activated carbon system costs $1,500–$3,000. Test first — a PFAS panel costs $300–$500.

What Are PFAS and Why Are They in Your Well?

PFAS are synthetic chemicals invented in the 1940s. They make things nonstick, waterproof, and stain-resistant. They are in cookware, clothing, food packaging, and firefighting foam.

Think of them as chemicals that refuse to die. Once they enter the ground, they stay. They move through soil into groundwater — and into your well[6].

Common sources near private wells:

  • Military bases and airports: Firefighting foam (AFFF) contains high levels of PFAS. Decades of training exercises pushed them into the ground.
  • Landfills: Consumer products with PFAS break down in landfills and leach into groundwater.
  • Industrial sites: Factories that made or used PFAS contaminated surrounding land and water.
  • Wastewater treatment plants: Biosolids (treated sewage) applied as fertilizer spread PFAS across farmland[10].

Have your water test results handy? Get a treatment plan based on your exact numbers.

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Health Risks of PFAS in Water

PFAS accumulate in your body over time. Your body cannot break them down. Health effects are linked to long-term exposure[3].

Research has connected PFAS exposure to:

  • Thyroid disease: PFAS disrupt thyroid hormone production.
  • Liver damage: Elevated liver enzymes at higher exposure levels.
  • Immune suppression: Reduced vaccine response in children and adults.
  • Cancer: Increased risk of kidney and testicular cancer[7].
  • Reproductive harm: Linked to preeclampsia, low birth weight, and fertility issues.
  • High cholesterol: PFAS exposure raises cholesterol levels.

The National Academies of Sciences recommends clinical follow-up for people with significant PFAS exposure[7].

What Your PFAS Level Means

PFAS are measured in ppt (parts per trillion). That is 1,000 times smaller than ppbPPB (Parts Per Billion)A unit of concentration equivalent to micrograms per liter (µg/L). Used for trace contaminants like arsenic, lead, and PFAS where even tiny amounts matter.Learn more → (parts per billion). Even tiny amounts matter.

Level (PFOA or PFOS) Status What It Means What to Do
0–2 ppt Low Risk Below detection at most labs. No action needed. Retest in 3–5 years.
2–4 ppt Caution Approaching EPA MCL. Consider treatment. Retest annually.
4–20 ppt Action Needed Exceeds EPA MCL for PFOA/PFOS. Install RO or GAC filter. Retest after treatment.
20+ ppt Urgent Significantly elevated. Use bottled water for drinking/cooking. Install RO immediately.

These levels apply to PFOA and PFOS individually[1]. The EPA also set a combined hazard index for other PFAS compounds. If your total PFAS level is high, treatment is still recommended even if individual compounds are below 4 ppt.

How to Test for PFAS in Well Water

Standard well water tests do not include PFAS. You must request a specific PFAS panel.

Cost: $300–$500 for a comprehensive panel (18–40+ compounds). Some states offer free testing for wells near known contamination sites.

Use a lab certified for EPA Method 533 or 537.1. These methods detect PFAS at ppt levels[6]. Mail-in services like Tap Score and SimpleLab offer PFAS panels.

Should you test? Yes, if you live within 5 miles of a military base, airport, landfill, or industrial site. The Environmental Working Group maintains a PFAS contamination map[8].

3 Ways to Remove PFAS from Well Water

Under-Sink Reverse Osmosis ($200–$600)

RO pushes water through a membrane with pores too small for PFAS to pass through. It removes 90–99% of PFOA, PFOS, and most other PFAS compounds[4].

Best for: Drinking and cooking water. This is the most effective and affordable option for most households.

Compare RO systems for well water

Whole-House Granular Activated Carbon ($1,500–$3,000)

A GAC system uses activated carbonCatalytic CarbonA specialized activated carbon filter media that removes hydrogen sulfide, iron, and chlorine through catalytic reaction rather than simple adsorption. Effective for iron under 3 ppm.Learn more → (a porous filter media that traps chemicals) to adsorb PFAS from all water entering your home. Removal rates vary: 60–95% depending on the specific PFAS compound and contact time[5].

GAC is better for longer-chain PFAS (PFOA, PFOS) than shorter-chain compounds. Carbon needs replacement every 1–3 years ($300–$600 per change).

Best for: Whole-home protection. Reduces PFAS in showers and all taps.

Ion Exchange Resin System ($2,000–$4,000)

Ion exchangeIon ExchangeA treatment process where unwanted ions (calcium, magnesium, iron) are swapped for sodium or potassium ions as water passes through a resin bed. The principle behind water softeners.Learn more → (a process that swaps harmful ions for harmless ones) resins designed for PFAS achieve 95%+ removal. They are more effective than GAC for short-chain PFAS[5].

Best for: Wells with high PFAS levels or a mix of short- and long-chain compounds. Higher upfront cost, but the most thorough whole-house option.

DIY vs. Professional Installation

Under-sink RO: DIY-friendly. 1–2 hours with basic tools.

Whole-house GAC or ion exchange: Professional recommended. These connect to your main water line and need proper sizing. Professional installation adds $300–$800.

What to Do Next

Not sure if you're at risk? Check the PFAS contamination map for known sites near your home[8]. If anything is within 5 miles, test your water.

Have test results? Use our Water Test Interpreter for a treatment plan.

Ready to filter? Read our Best Reverse Osmosis Systems comparison. RO is the most cost-effective way to remove PFAS at the point of use.

Frequently Asked Questions

What are PFAS in well water?

PFAS are synthetic chemicals used in nonstick coatings, firefighting foam, and food packaging. They are called "forever chemicals" because they do not break down. They enter groundwater from industrial sites, military bases, airports, and landfills[6].

What is the EPA limit for PFAS?

The EPA set enforceable limits in April 2024: 4 ppt for PFOA and 4 ppt for PFOS individually[1]. These apply to public systems but serve as the best benchmark for private wells.

How much does PFAS testing cost?

A comprehensive PFAS panel costs $300–$500. Some states offer free testing for wells near known contamination sites. Use a lab certified for EPA Method 533 or 537.1.

Do water filters remove PFAS?

Yes. RO systems remove 90–99% of PFAS. Activated carbon removes 60–95%. Ion exchange resins achieve 95%+[4]. Look for NSF/ANSI 53 or 58 certification with PFAS listed.

Is my well at risk?

Higher risk if you are within 5 miles of a military base, airport, landfill, or industrial site. A USGS study found PFAS in 45% of U.S. tap water[2]. Private wells are not regulated — testing is your responsibility.

References

  1. U.S. EPA. "PFAS National Primary Drinking Water Regulation." Final Rule, April 2024. https://www.epa.gov/pfas
  2. U.S. Geological Survey. "Tap Water Study Detects PFAS in 45% of U.S. Drinking Water." 2023. https://www.usgs.gov/news/national-news-release/tap-water-study-detects-pfas-forever-chemicals-45-nations-drinking-water
  3. Agency for Toxic Substances and Disease Registry. "PFAS Health Effects." CDC/ATSDR, 2024. https://www.atsdr.cdc.gov/pfas/
  4. NSF International. "NSF/ANSI 53 & 58: PFAS Reduction Testing Protocols." 2024. https://www.nsf.org
  5. Water Quality Association. "PFAS Treatment Technologies for Point-of-Use and Point-of-Entry." 2024. https://wqa.org
  6. Interstate Technology Regulatory Council. "PFAS Technical and Regulatory Guidance." 2023. https://pfas-1.itrcweb.org
  7. National Academies of Sciences, Engineering, and Medicine. "Guidance on PFAS Exposure, Testing, and Clinical Follow-Up." 2022.
  8. Environmental Working Group. "PFAS Contamination Map." 2024. https://www.ewg.org/interactive-maps/pfas_contamination/
  9. U.S. EPA. "Drinking Water Health Advisories for PFOA and PFOS." 2022. https://www.epa.gov/pfas
  10. Duke University. "PFAS in Private Well Water Near Contamination Sources." Nicholas School of the Environment, 2023.