PFAS in drinking water

PFAS — per- and polyfluoroalkyl substances — are a large family of manufactured chemicals used since the 1940s in products that resist heat, water, and grease. They break down very slowly, which is why they are often called forever chemicals, and they have been detected in drinking water across the United States. The EPA set the first enforceable federal limits for six PFAS in April 2024. As of October 2026 the limits for PFOA and PFOS stand at 4 parts per trillion, while the limits for four other PFAS are the subject of a proposed rescission and ongoing federal litigation. North Carolina's Cape Fear River basin is among the most heavily studied PFAS-affected regions in the country. This article covers where PFAS come from, what the regulations currently require, how to find out what is in your own water, and which treatment approaches carry certification for PFAS reduction.

Why this matters

PFAS are different from most drinking water contaminants in three ways that affect how people think about them. They persist — in the environment and in the body — rather than clearing quickly. They are regulated at parts per trillion rather than parts per billion or million, concentrations so low that they sit near the edge of what laboratories can reliably measure. And the regulatory picture is actively moving, which means a reader who learned the rules a year ago may be working from an outdated understanding.

This article is for anyone trying to understand what PFAS are, whether they are present in their water, and what the options are for reducing them.

What PFAS are

PFAS are a family of several thousand synthetic chemicals built around chains of carbon and fluorine. The carbon-fluorine bond is one of the strongest in organic chemistry, which is what gives these compounds their useful properties — resistance to heat, water, oil, and stains — and also what makes them persist for years or decades rather than breaking down.

They have been manufactured since the 1940s and used in nonstick cookware, waterproof and stain-resistant fabrics, food packaging, cosmetics, and firefighting foam, among many other applications. Production of some of the older compounds has been phased out in the United States, but the compounds already released remain in the environment, and newer replacement compounds are also PFAS.

A few names come up repeatedly in drinking water contexts:

• PFOA (perfluorooctanoic acid) and PFOS (perfluorooctane sulfonate) are the two most studied. Both were largely phased out of U.S. production in the 2000s but remain widespread in the environment.
• GenX chemicals, more precisely HFPO-DA, were developed as a replacement for PFOA. They are the compounds most closely associated with the Cape Fear River contamination in North Carolina.
• PFHxS, PFNA, and PFBS appear in federal monitoring and in the 2024 regulation.

Health research on PFAS has linked certain compounds to effects on the immune system, cholesterol levels, liver enzymes, thyroid function, birth weight, and some cancers. The research is more developed for PFOA and PFOS than for newer compounds, and the Agency for Toxic Substances and Disease Registry maintains the most accessible overview for readers who want the detail.

How PFAS reach drinking water

PFAS enter water supplies through several routes, and which one applies shapes what can be done about it.

Industrial discharge. Facilities that manufacture or use PFAS have historically discharged them into surface water and groundwater. This is the dominant pathway in the Cape Fear basin and in several other well-documented cases nationally.

Firefighting foam. Aqueous film-forming foam used at airports, military installations, and fire training facilities contains PFAS and has contaminated groundwater at many such sites. Private wells near these sites are a particular concern.

Landfills and biosolids. PFAS in consumer products reach landfills, and leachate can carry them into groundwater. Treated sewage sludge applied to agricultural land is another documented pathway.

Atmospheric deposition. PFAS released to air settle onto land and water, which is part of why low-level detections are so widespread.

The regional picture

North Carolina's Cape Fear River basin is one of the most studied PFAS-affected regions in the country. In 2017 it became publicly known that the Chemours facility at Fayetteville Works had for decades been discharging PFAS, including GenX compounds, into the Cape Fear River. The river is the drinking water source for communities across southeastern North Carolina, including the Wilmington area.

Public water utilities in the region have since invested heavily in treatment. The Cape Fear Public Utility Authority spent more than $43 million on treatment at a single facility. Ongoing research includes a long-running study measuring PFAS in the blood of residents in the basin.

The North Carolina Department of Environmental Quality has estimated that roughly 3.5 million North Carolinians drink water with PFAS levels above the federal standards. PFAS detections are not confined to the Cape Fear basin, and the Haw River — a Cape Fear tributary running through the Piedmont — has its own documented history of PFAS and 1,4-dioxane concerns.

Private wells are a separate situation. Wells near industrial sites, airports, military installations, fire training facilities, or land where biosolids have been applied are at higher risk, and no one is monitoring a private well unless the owner arranges it.

Where the regulations stand

This section describes the regulatory position as of October 2026. It is an actively moving area, and anyone making decisions on the strength of it should verify the current status against the EPA sources linked below.

The 2024 rule

In April 2024 the EPA finalized the first enforceable federal drinking water standards for PFAS — a National Primary Drinking Water Regulation covering six compounds:

The Maximum Contaminant Level Goals for PFOA and PFOS are zero, reflecting the EPA position that no level of exposure to these compounds is presumed entirely without risk. Our article on EPA drinking water standards explains how MCLs and MCLGs differ and why the two numbers are not the same.

The rule requires public water systems to complete initial PFAS monitoring by 2027 and to meet the limits by April 2029. Systems exceeding a limit must either find an alternative source or install treatment the EPA recognizes as a best available technology for PFAS — granular activated carbon, ion exchange, or reverse osmosis.

What changed in 2026

In May 2026 the EPA proposed two rules that would modify the 2024 regulation. Both were published on May 20, 2026, and the public comment period closed on July 20, 2026. The EPA has stated it intends to take final action in 2026.

The proposed compliance extension would push the PFOA and PFOS deadline from April 2029 to April 2031, through a framework under which eligible water systems could apply for additional time. Systems granted an extension would be required to implement interim control measures and hold PFAS below 12 parts per trillion during the extension period.

The proposed rescission would withdraw the regulatory determinations and the resulting limits for four of the six compounds — PFHxS, PFNA, HFPO-DA (GenX), and the Hazard Index for mixtures. The EPA's stated basis is procedural: the agency's position is that the 2024 rulemaking did not follow the sequence the Safe Drinking Water Act requires for these four compounds, specifically regarding the timing of regulatory determinations relative to proposed regulations. The EPA has said the rescission is not based on a reassessment of the health or occurrence data, and that it intends to reevaluate these four compounds for possible future regulation.

The limits for PFOA and PFOS at 4 parts per trillion are retained in both proposals.

These proposals have drawn substantial comment in both directions. Water utilities and some industry groups argued the original timelines and the four additional standards imposed costs and compliance burdens the statute did not support. Public health organizations, environmental groups, and a number of state attorneys general argued that withdrawing standards already finalized conflicts with the Safe Drinking Water Act's provision against weakening existing drinking water protections. In the Cape Fear region specifically, the proposed rescission of the GenX standard drew strong objection from local advocacy organizations and utilities that had already invested in treatment.

The litigation

Separately from the rulemaking, the 2024 regulation is being challenged in the U.S. Court of Appeals for the D.C. Circuit in American Water Works Association et al. v. EPA. Industry and water utility petitioners challenged the rule on cost and procedural grounds; public health organizations intervened in support of it. The EPA has continued to defend the PFOA and PFOS standards while declining to defend the four it has proposed to rescind. Oral argument was held in January 2026. The court declined to vacate the four standards in advance, choosing instead to consider the challenges together.

What this means in practice for a reader today: the 2024 limits remain the law unless and until the rescission is finalized or a court orders otherwise. Public water systems are still working toward the monitoring deadline. The compliance deadline for treatment may move. Readers should not assume any particular outcome.

State-level standards

States may set drinking water standards stricter than the federal floor, and some have. North Carolina has not established enforceable state-level drinking water standards for PFAS, so federal limits are what apply to public water systems in the state.

North Carolina has set groundwater standards for three PFAS under its 2L rules, effective November 1, 2025, covering PFOA, PFOS, and HFPO-DA. These are groundwater standards rather than drinking water standards — they govern groundwater quality and bear on contamination assessment and remediation rather than on what a public water system must deliver at the tap. The distinction matters when reading state materials, because the two kinds of standard are easy to conflate.

Virginia likewise relies on the federal standards for public water system compliance.

How to find out what is in your water

PFAS cannot be tasted, smelled, or seen. Testing is the only way to know, and it requires a laboratory using methods developed specifically for drinking water — EPA Method 533 or 537.1. Not every certified laboratory offers PFAS analysis, and home test kits cannot detect at the concentrations that matter.

If you are on a municipal system, three sources are worth checking:

• Your utility's Consumer Confidence Report. PFAS results will appear as monitoring under the 2024 rule rolls out. Older reports may not include PFAS at all, which reflects the monitoring timeline rather than an absence of PFAS.
• The EPA's UCMR 5 data. The fifth Unregulated Contaminant Monitoring Rule cycle collected PFAS occurrence data from public water systems nationally between 2023 and early 2026. This is the most comprehensive public dataset on where PFAS have been detected and at what levels.
• Your own tap test. A utility-level result describes water leaving the treatment plant. A tap test describes your tap. For PFAS specifically the difference is usually small, since PFAS are not typically introduced by premises plumbing the way lead is — but a tap test confirms it for your household.

If you are on a private well, no one is testing unless you arrange it. Testing is worth considering for any well, and particularly where the property is near an industrial site, an airport or military installation, a fire training facility, a landfill, or farmland where biosolids have been applied. Our article on testing your water covers how to find a certified laboratory and read the result.

Results are reported in parts per trillion (ppt) or nanograms per liter (ng/L) — the two are equivalent. Note the unit carefully, since most other contaminants on a water report are expressed in parts per billion or parts per million, which are a thousand and a million times larger.

Treatment that reduces PFAS

Three technologies are recognized by the EPA as best available technologies for PFAS in public water systems, and all three have residential equivalents.

Granular activated carbon. Carbon adsorbs PFAS onto its surface. At whole-house scale this is a tank of carbon media on the main line treating all water entering the home. Capacity is finite — the media eventually saturates and needs replacement — and the interval depends on the concentration in the water and the volume used.

Ion exchange. Specialized resins designed to capture PFAS, distinct from the cation exchange resin in a water softener. A standard softener is not a PFAS treatment.

Reverse osmosis. The membrane rejects PFAS along with a broad range of other dissolved contaminants. Under-sink RO treats the drinking and cooking tap; whole-home RO treats everything. Our article on reverse osmosis covers both configurations and how the stages around the membrane are selected.

Several things do not reduce PFAS, and two of them are common assumptions worth correcting:

• Boiling does not help. PFAS do not evaporate with the water, so boiling concentrates them rather than removing them.
• Water softeners do not address PFAS. Softeners treat hardness through cation exchange; PFAS are not hardness minerals.
• Standard sediment filters and most basic carbon pitcher filters are not designed for PFAS and generally carry no certification for it.

Reading certification claims

This is where PFAS treatment decisions most often go wrong, and the distinction is worth understanding before comparing any two products.

NSF/ANSI Standard 53 covers drinking water treatment units for health effects, and NSF/ANSI Standard 58 covers reverse osmosis systems. A product can carry either certification without being certified for PFAS, because these certifications are issued per contaminant, not as a blanket. A filter certified under Standard 53 for chlorine, cysts, or lead is a legitimately certified product that may have no PFAS certification at all.

So the question to ask is not whether a product is NSF certified. It is whether PFAS specifically appears on that product's certified reduction list. The certifying body's public listing is the place to confirm it — NSF, IAPMO, and WQA each publish searchable databases of certified products and their certified claims.

Worth knowing: whole-house certified PFAS reduction is less common than point-of-use. Most certified PFAS products are under-sink or faucet-mounted, treating the consumption tap. Whole-house carbon systems certified under Standard 53 for PFAS reduction do exist, and some are designed to operate without backwashing, without a drain connection, and without electricity, which simplifies installation considerably compared with systems that need all three.

Point-of-use or whole house

Both approaches are in use, and the choice turns on what the household wants treated.

Point-of-use treats the tap where you drink and cook. Since ingestion is the primary exposure route for PFAS, a certified under-sink filter or RO system addresses the main pathway at a fraction of the cost and complexity of whole-house treatment. For many households this is the whole answer.

Whole house treats everything — every tap, shower, appliance, and fixture. Some households want this because they drink from more than one tap, because children use bathroom taps, or because they would rather not have PFAS in any of their water regardless of which exposure route the research emphasizes. That is a coherent position, and whole-house carbon or whole-home RO delivers it.

Neither choice requires justifying to the other. A household that treats the kitchen tap and a household that treats the whole house are both addressing PFAS; they are addressing different amounts of it, at different cost.

Factors in the decision

Several things typically inform how a household approaches PFAS:

What your testing shows. A confirmed detection at or above the federal limits points clearly toward treatment. A low-level detection sits in the gap between the MCL and the MCLG of zero, where the decision is personal. A non-detect on a current, properly-methoded test is meaningful information.

Whether you are on a well or a municipal system. A municipal customer is inside a system that will be required to treat if it exceeds the limits, though the timeline may extend to 2031. A private well owner has no such backstop.

Household composition. Households with infants, people who are pregnant, or members with specific health considerations may weigh low-level detections differently than a household of healthy adults.

Which taps matter to you. Consumption-only coverage and whole-house coverage are different products at different prices.

How much certainty you want about the future. The regulatory picture is unsettled. A household that wants its own water handled regardless of how the rulemaking and litigation resolve may reasonably treat now rather than wait.

Cost and maintenance. Carbon media and RO membranes need periodic replacement. Whole-house systems carry larger media volumes and higher replacement costs than point-of-use. Operating cost is part of the comparison, not an afterthought.

When professional advice makes sense

Professional input is most useful when a test shows PFAS at or near the federal limits and you want help matching certified treatment to the specific compounds detected; when you are on a well near a known or suspected source; when PFAS appears alongside other concerns that need to be sequenced in one treatment train; when you are weighing point-of-use against whole-house coverage; or when you want help confirming that a specific product's certification actually covers PFAS rather than something else under the same standard.