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What Is PFAS and How to Remove It From Drinking Water

PFAS are in the news constantly, and for good reason. These synthetic chemicals — nicknamed “forever chemicals” because they don’t break down in the environment or in your body — have been found in the drinking water of communities across the United States. The EPA estimates that PFAS contamination affects the water supplies of approximately 100 million Americans. In April 2024, the EPA finalized the first-ever enforceable federal limits on PFAS in drinking water, setting maximum contaminant levels (MCLs) of just 4 parts per trillion for PFOA and PFOS — two of the most common and well-studied PFAS compounds.

But what exactly are these chemicals? How did they get into your water? What do they do to your health? And most importantly, how do you remove them? This article answers all of those questions with the facts you need to make informed decisions about your drinking water.

What Are PFAS?

PFAS stands for per- and polyfluoroalkyl substances — a family of over 15,000 synthetic chemicals that share a common feature: a chain of carbon atoms bonded to fluorine atoms. The carbon-fluorine bond is one of the strongest in organic chemistry, which is why these chemicals are extraordinarily resistant to heat, water, oil, and degradation. That durability made them incredibly useful in manufacturing — and incredibly persistent as pollutants.

PFAS have been manufactured since the 1940s and used in a staggering range of products:

The two most studied PFAS compounds are PFOA (perfluorooctanoic acid, used in making Teflon) and PFOS (perfluorooctane sulfonic acid, used in Scotchgard and firefighting foam). Both have been phased out of production in the US, but because they don’t break down, they persist in the environment — in soil, water, and in the blood of virtually every person on Earth.

How PFAS Get Into Drinking Water

PFAS enter water supplies through several pathways:

Firefighting foam (AFFF): This is the single largest source of PFAS water contamination. AFFF has been used for decades at military bases, airports, oil refineries, and fire training facilities. When the foam is sprayed, PFAS compounds soak into the ground and migrate into groundwater. Communities near military installations and airports are disproportionately affected.

Industrial discharge: Factories that manufacture or use PFAS release them into wastewater, which can contaminate rivers, lakes, and groundwater. Chemical plants, textile manufacturers, and electronics facilities are common sources.

Landfill leachate: Consumer products containing PFAS end up in landfills. As water percolates through the landfill, it picks up PFAS and can contaminate nearby groundwater.

Wastewater treatment plants: Conventional wastewater treatment does not remove PFAS. When treated wastewater is discharged into rivers or used for irrigation, PFAS enter the water cycle. Biosolids (treated sewage sludge) applied to agricultural land as fertilizer are another pathway.

Agricultural runoff: Crops irrigated with PFAS-contaminated water or grown in soil amended with contaminated biosolids can contribute to PFAS in groundwater.

Health Effects of PFAS Exposure

PFAS accumulate in the body over time — they have a half-life of several years in human blood, meaning it takes years for your body to eliminate even half of the PFAS you’ve absorbed. Research has linked PFAS exposure to a range of serious health effects:

Cancer: PFOA has been classified as a possible human carcinogen. Studies have found associations between PFAS exposure and kidney cancer, testicular cancer, and other cancers. The EPA’s 2024 risk assessment concluded that there is no safe level of PFOA or PFOS exposure.

Immune system suppression: PFAS exposure has been shown to reduce the effectiveness of vaccines and weaken the immune response. This is particularly concerning for children, whose immune systems are still developing.

Thyroid disease: PFAS can interfere with thyroid hormone production, leading to hypothyroidism and other thyroid disorders.

Liver damage: Studies have found associations between PFAS exposure and elevated liver enzymes, non-alcoholic fatty liver disease, and other liver effects.

Reproductive effects: PFAS exposure has been linked to reduced fertility, pregnancy-induced hypertension, preeclampsia, and low birth weight.

Developmental effects in children: Prenatal and early childhood PFAS exposure has been associated with developmental delays, behavioral changes, and accelerated puberty.

Cholesterol: Even at low exposure levels, PFAS have been consistently associated with elevated cholesterol levels, which increases cardiovascular disease risk.

EPA Regulations: The 2024 PFAS Rule

In April 2024, the EPA finalized the first-ever National Primary Drinking Water Regulation for PFAS. Here’s what the rule established:

Option A

Option B

To put 4 parts per trillion in perspective: that’s equivalent to 4 drops of water in an Olympic-sized swimming pool. These are among the lowest MCLs ever set for any drinking water contaminant, reflecting the EPA’s assessment that PFAS are harmful at extremely low concentrations.

Compliance timeline: Public water systems must complete initial PFAS monitoring by 2027 and comply with the MCLs by 2029 (with some extensions to 2031 for systems that need additional time to install treatment). Systems that exceed the MCLs must notify customers and implement treatment or find alternative water sources.

Important note: These regulations apply only to public water systems. Private wells are not covered. If you’re on a private well, you’re responsible for testing your own water for PFAS and installing treatment if needed.

Regulatory update: In 2025, the EPA revised the rule, retaining the MCLs for PFOA and PFOS but rescinding the limits for some other PFAS compounds. The 4 ppt limits for PFOA and PFOS remain in effect and are the most critical standards for consumers to be aware of.

Is PFAS in Your Water?

If you’re on municipal water: Check your utility’s Consumer Confidence Report (CCR). As utilities begin PFAS monitoring under the 2024 rule, PFAS results will appear in CCRs. You can also check the EWG’s PFAS contamination map (ewg.org/interactive-maps/pfas_contamination) to see if PFAS have been detected in your area. If your utility hasn’t tested yet, or if you want to know what’s reaching your specific tap, a home water test from a certified lab can detect PFAS at the parts-per-trillion level.

If you’re on a private well: The only way to know is to test. PFAS testing for well water is available through certified labs and mail-in services like Tap Score. A PFAS-specific test typically costs $200-$400. Testing is especially important if your well is within a few miles of a military base, airport, fire training facility, industrial site, or landfill.

How to Remove PFAS From Drinking Water

Not all water filters remove PFAS. Standard pitcher filters, basic faucet-mount filters, and simple carbon filters are generally not effective against PFAS at the parts-per-trillion level. Here are the technologies that work:

Reverse Osmosis (Most Effective)

RO systems force water through a semi-permeable membrane with pores small enough to reject PFAS molecules. Well-designed RO systems remove 90-99% of PFOA and PFOS, making them the most effective residential option for PFAS removal.

Activated Carbon Filtration (Effective When Properly Designed)

High-quality activated carbon filters — particularly carbon block filters and granular activated carbon (GAC) systems — can reduce PFAS significantly, but effectiveness varies widely depending on the carbon type, contact time, and filter design. Not all carbon filters are equal for PFAS.

Pitcher filters with PFAS certification: A few pitcher filters have been independently tested and certified for PFAS reduction. Clearly Filtered and Epic Water Filters are among the brands with documented PFAS reduction claims. Standard Brita and PUR pitcher filters are not certified for PFAS removal.

Ion Exchange (Effective but Less Common Residentially)

Specialized ion exchange resins can remove PFAS by exchanging PFAS molecules for harmless ions. This technology is highly effective (up to 99% removal) and is widely used in municipal treatment plants. Residential ion exchange systems for PFAS are less common but available.

What Doesn’t Work for PFAS

Choosing the Right PFAS Filter

When shopping for a PFAS filter, the most important thing is certification. Look for:

  1. NSF/ANSI 53 with PFOA and PFOS listed as certified contaminants — this is the current standard for carbon-based filters
  2. NSF/ANSI 58 with PFAS claims — for reverse osmosis systems
  3. NSF P473 — the original PFAS-specific protocol (still valid on existing products)

A filter that’s “NSF 53 certified” but not specifically certified for PFAS may not reduce PFAS at all. The certification must list PFOA and/or PFOS as specific contaminants the filter is tested and certified to reduce. Verify on the NSF, WQA, or IAPMO online databases.

Reducing PFAS Exposure Beyond Water

While filtering your drinking water is the most impactful step, PFAS exposure comes from multiple sources:

Frequently Asked Questions

Can you taste or smell PFAS in water?

No. PFAS are odorless, tasteless, and invisible in water. You cannot detect them without laboratory testing. Water that looks, tastes, and smells perfectly fine can contain PFAS at levels above the EPA’s MCL.

Are PFAS only a problem near military bases?

No. While military bases and airports are major sources due to firefighting foam use, PFAS contamination is widespread. Industrial facilities, landfills, wastewater treatment plants, and even agricultural land treated with biosolids can be sources. PFAS have been detected in water supplies in all 50 states.

If my water utility is treating for PFAS, do I still need a home filter?

It depends on your utility’s treatment effectiveness and your comfort level. Utilities that install PFAS treatment should reduce levels below the MCL, but treatment effectiveness can vary, and the MCLGs for PFOA and PFOS are zero — meaning any reduction below the MCL is still beneficial. A home RO system or certified carbon filter provides an additional layer of protection.

How much does PFAS water testing cost?

A PFAS-specific water test from a certified lab typically costs $200-$400. Companies like Tap Score offer PFAS test kits that you collect at home and mail to their lab. Some state health departments offer free or subsidized PFAS testing for private well owners in known contamination areas — check with your state environmental agency.

Do whole-house filters remove PFAS?

Whole-house granular activated carbon filters can reduce PFAS to some degree, but they’re generally less effective than point-of-use systems (under-sink RO or carbon block filters) because the water moves through the carbon faster, reducing contact time. For PFAS specifically, a point-of-use system at the kitchen tap is more reliable and cost-effective than trying to treat all water in the house.

The Bottom Line

PFAS are a real and widespread drinking water contaminant with documented health effects at very low concentrations. The EPA’s 2024 rule setting MCLs at 4 ppt for PFOA and PFOS reflects the scientific consensus that these chemicals are harmful even in trace amounts. If you’re concerned about PFAS — and the data suggests you should be — test your water, and if PFAS are detected, install a reverse osmosis system or a carbon filter specifically certified for PFAS reduction. Certification matters: look for NSF 53 or NSF 58 with PFAS listed as a certified contaminant, and verify it in the certifying body’s online database.

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