What Is PFAS?
PFAS stands for per- and polyfluoroalkyl substances. These are human-made chemicals that have been used for decades in industrial applications and consumer products because they resist heat, water, and oil. (EPA)
PFAS is not one chemical. It is a category that includes thousands of different compounds. Research is still catching up to how many exist and how they behave. (EPA)
Many PFAS do not break down easily in the environment. This persistence is why they are often called "forever chemicals." (NSF)
Common PFAS you may see on test reports include:
- PFOA (perfluorooctanoic acid)
- PFOS (perfluorooctane sulfonate)
- PFHxS (perfluorohexane sulfonate)
- PFNA (perfluorononanoic acid)
- GenX chemicals (HFPO-DA)
Why PFAS in Well Water Matters
PFAS health research is complex. Effects can depend on which PFAS, how much, and how long exposure occurs. EPA notes that health effects are difficult to determine precisely because of the large number of PFAS and changing exposures over time. (EPA)
Research suggests that exposure to some PFAS may be associated with: (ATSDR)
- Increased cholesterol levels
- Reduced antibody response to some vaccines
- Changes in liver enzymes
- Pregnancy-related high blood pressure
- Small decreases in birth weight
- Kidney and testicular cancer (for certain PFAS in some studies)
Pregnant and lactating people and young children can have higher exposure per body weight because they drink more water relative to their size. Infants can be exposed through formula made with contaminated water. (EPA)
Where PFAS in Well Water Comes From
PFAS can enter the environment during manufacturing, product use, and disposal. Over time, it can reach surface water and groundwater. (NSF)
Firefighting Foam (AFFF)
Aqueous film-forming foam was widely used for fuel fires at airports and military facilities. Many PFAS investigations involving private wells trace back to historic AFFF use.
Industrial Sites
Some PFAS were produced or used in manufacturing. Living near PFAS-producing or PFAS-using facilities is one factor EPA highlights for higher exposure potential. (EPA)
Landfills and Waste Sites
PFAS-containing products and industrial wastes can contribute to contamination in groundwater near disposal areas.
Widespread Background Levels
PFAS has been detected broadly across the U.S. USGS research suggests a significant share of tap water may contain at least one PFAS, though detection depends on what is tested for. (USGS)
Why Private Wells Are Vulnerable
Public water systems must monitor and meet federal drinking water rules. Private wells typically do not have that built-in monitoring.
If PFAS enters your groundwater, you will not know unless you test. State programs may offer testing in certain areas, but coverage varies widely.
USGS has mapped where PFAS occurrence is more likely at depths used by public and private supply wells. Whether contamination reaches a specific well depends on local geology, well depth, distance from sources, and pumping patterns. (USGS)
When to Test for PFAS in Well Water
PFAS testing is not needed every year for most locations. It is best used when your location or circumstances suggest elevated risk.
Consider PFAS testing if:
- You are near a known PFAS investigation area (state notice, county notice, or mapped plume)
- You are near likely sources: airports, military bases, industrial facilities, or landfills
- Neighbors have detected PFAS, especially if wells share the same aquifer
- You are buying a property with a private well in a potentially affected area
- You have infants, pregnancy, or immunocompromised household members (EPA)
- You are installing new treatment equipment or drilling a new well
Check your state environmental agency's PFAS pages and any local advisories to determine whether PFAS is a priority test for your location.
How to Test for PFAS
What PFAS Tests Measure
Most PFAS tests use EPA laboratory methods 533 or 537.1, which measure 29 specific PFAS compounds. A "non-detect" result means those specific compounds were not found above the reporting limit. Other PFAS not on the list are not evaluated. (EPA)
Sampling Requirements
PFAS can be present at very low concentrations (parts per trillion), so sampling needs extra care:
- Use the lab's containers and follow instructions exactly
- Do not substitute different bottles or household containers
- Many kits include a field blank to detect contamination during sampling
Connecticut DEEP notes that labs may provide containers for both a primary sample and a field blank, which may be billed separately. (CT DEEP)
Choosing a Lab
Look for a lab that:
- Uses EPA drinking water PFAS methods (533 or 537.1)
- Has state certification for drinking water PFAS analysis
- Provides clear chain-of-custody and sampling guidance
- Reports detection limits so you can interpret results correctly
Cost and Turnaround
PFAS testing typically costs $300 or more per sample. Results often take 2 to 3 weeks. (CT DEEP)
How to Interpret PFAS Test Results
Units
PFAS results are reported in ng/L (nanograms per liter) or ppt (parts per trillion). In water, 1 ng/L equals 1 ppt.
EPA Standards (2024 Rule)
EPA finalized drinking water standards for public systems in 2024: (EPA)
- PFOA: 4 ppt
- PFOS: 4 ppt
- PFHxS: 10 ppt
- PFNA: 10 ppt
- GenX (HFPO-DA): 10 ppt
The rule also includes a Hazard Index approach for mixtures of certain PFAS.
What the Numbers Mean for Private Wells
Federal standards apply to public water systems, not private wells. However, they serve as useful reference points. Compare your results to:
- Any state guidance for private wells
- Federal MCLs as a reference
- Local investigation thresholds if you are in a known contamination area
Non-Detect Does Not Mean PFAS-Free
A non-detect result means the lab did not find the tested compounds above the reporting limit. Other PFAS not included in the test panel are not evaluated.
What to Do if PFAS Is Found
Step 1: Confirm the Result
Check whether a field blank was analyzed and whether it was clean. Consider confirmatory sampling if results are close to an action level or if sample handling was uncertain.
Step 2: Reduce Exposure
If results are clearly elevated:
- Use an alternative source for drinking and cooking until you have a plan
- Do not boil water. Boiling does not remove PFAS and can concentrate it if water evaporates (NSF)
Step 3: Consider Treatment
Common treatment options for PFAS include:
- Activated carbon (granular or carbon block)
- Reverse osmosis at the point of use
- Ion exchange for whole-house applications
Look for filters certified to NSF/ANSI Standard 53 or Standard 58 for PFAS reduction. NSF provides tools to search certified products. (NSF)
Step 4: Retest After Treatment
Test the treated water after installation to verify the system is working. Retest periodically based on filter replacement schedules.
Prevention and Maintenance Tips
You cannot prevent PFAS from entering groundwater from distant sources. But you can manage exposure:
- Know your location: Check state PFAS investigation maps and local advisories
- Test when risk factors apply: Near airports, military bases, industrial sites, or landfills
- Maintain treatment systems: Replace filters on schedule per manufacturer instructions
- Retest periodically: Verify treatment continues working, especially after filter changes
- Keep records: Save test results to track changes over time
Frequently Asked Questions
Is PFAS in well water common?
PFAS has been detected widely across the U.S., but occurrence varies by location, what PFAS are tested for, and proximity to sources. USGS research shows PFAS can occur in groundwater used for drinking water, including areas that rely on private wells.
Can I taste or smell PFAS in my well water?
No. PFAS at levels of concern generally has no reliable taste, smell, or appearance. Testing is the only way to know if it is present.
How much does PFAS testing cost for a private well?
PFAS testing typically costs $300 or more per sample. Costs can increase if field blanks are billed separately or if you request a larger panel of compounds.
How long do PFAS test results take?
Results are often reported within 2 to 3 weeks, though timing varies by lab and workload.
Do standard well water tests include PFAS?
Usually not. Typical well potability panels focus on bacteria, nitrates, metals, and basic chemistry. PFAS is a specialty test that must be requested separately.
Does boiling water remove PFAS?
No. Boiling does not remove PFAS and can actually concentrate it as water evaporates. Use certified filtration instead.
What filters remove PFAS from well water?
Activated carbon and reverse osmosis are commonly used. Look for filters certified to NSF/ANSI Standard 53 or 58 specifically for PFAS reduction.
What is the EPA limit for PFAS in drinking water?
EPA's 2024 rule set limits of 4 ppt for PFOA and PFOS, and 10 ppt for PFHxS, PFNA, and GenX in public water systems. These serve as reference points for private wells, though they do not directly regulate private wells.