Per- and polyfluoroalkyl substances (PFAS) have been the headline-grabbing “contaminant of the moment” across the water sector, driving a remarkable wave of regulation, litigation and treatment innovation. Their persistence, mobility and resistance to degradation have led to widespread presence in soil, water and even human bloodstreams, where they are correlated with the increased risk of some cancers, suppressed immunity, developmental delays in children, decreased fertility and high blood pressure in pregnant women.

Federal and state enforceable drinking water standards and compliance timelines are tightening, pushing utilities to face hard decisions about treatment system design, media supply and long-term liability. This column examines the regulatory landscape, primary treatment options and a looming constraint engineers can’t ignore: potential activated carbon shortages in a PFAS-driven market.

Where Things Stand on Regulations

In April 2024 the U.S. Environmental Protection Agency (EPA) finalized its first National Primary Drinking Water Regulation (NPDWR) for PFAS, establishing legally enforceable Maximum Contaminant Levels (MCLs) for six PFAS compounds in public drinking water. That rule set individual limits for PFOA, PFOS, PFHxS, PFNA and HFPO-DA and a Hazard Index limit for mixtures of PFHxS, PFNA, HFPO-DA and PFBS, and set monitoring, reporting and compliance timelines under the Safe Drinking Water Act. The regulation requires public water systems to monitor and report PFAS results to the public beginning 2027 and to comply starting April 2029.

In 2025, new EPA leadership announced its intent to retain the PFOA and PFOS standards but modify other parts of the regulation, and on May 20, 2026, the EPA initiated formal rulemaking for these changes.

In the first proposed rule change, the EPA would allow eligible water systems to seek additional time for compliance, from 2029 to 2031. This is not an across-the-board compliance deadline extension; water systems would need to apply for an extension and demonstrate why they are unable to meet the original 2029 deadline. Also, systems with PFOA or PFOS concentrations of 12ppt or greater must still implement short-term exposure reduction measures during the extension period. The second proposed rule change would rescind the standards for the remaining PFAS compounds and mixture hazard index.

The proposals are now subject to a 60-day public comment period that ends July 20, 2026, with a public hearing scheduled for July 7. Until these changes are finalized, all standards and deadlines in the 2024 PFAS NPDWR remain in force and enforceable. (Side note: the EPA also recently announced nearly $1 billion in newly available funding through the Emerging Contaminants in Small or Disadvantaged Communities grant program to help water systems address PFAS and other emerging contaminants.)

Meanwhile, many states have adopted PFAS standards that are stricter than federal requirements. Some are responding to the potentially weaker federal PFAS restrictions by rushing to codify parts or all the 2024 PFAS NPDWR into state law.

To navigate this patchwork of regulations, utilities should proceed with planning and implementing monitoring and treatment efforts based on the 2024 NPDWR and consult their state primacy agencies to understand state-level action.

Treatment Technologies for PFAS in Municipal Drinking Water

The leading PFAS treatment approaches fall into three primary categories: adsorption, membrane separation and destruction.

Adsorption remains the dominant municipal compliance strategy. Through adsorption, physical and chemical forces pull contaminants from the water and attach them to the surface of the adsorbent. Adsorption does not destroy PFAS but concentrates and traps them in the media, which will eventually become saturated and require reactivation or replacement.

Activated carbon is an adsorption media that is recognized by the EPA as a BAT for certain PFAS. It is widely deployed because it is proven, comparatively simple to design and relatively low in capital and operating costs. It’s particularly effective for long-chain PFAS such as PFOA and PFOS – the two PFAS compounds that the EPA has confirmed that it will continue to regulate in drinking water. Granular activated carbon (GAC) is considered the most cost-effective long-term technology, while powdered activated carbon (PAC) can be an excellent option for small systems and short-term needs because of its low start-up and capital costs and immediate efficacy.

Engineered polymeric ion exchange (IX) resin is an alternative adsorption pathway that can demonstrate higher capacity than activated carbon and stronger performance for short-chain PFAS. The tradeoffs include higher media cost and sensitivity to competing anions and fouling. Like activated carbon, IX removes but does not destroy PFAS.

Membrane separation technologies like reverse osmosis and nanofiltration can achieve very high rejection rates for both short- and long-chain PFAS compounds as well as salts, hardness and other dissolved constituents. Downsides include higher capital and operating costs and a PFAS-concentrated reject stream that must be managed. Fouling control and post-treatment remineralization may also be required. Membranes are often more common in groundwater systems with stable chemistry or in facilities that already employ desalination.

Foam fractionation (FF) uses air bubbles to leverage the surfactant properties of PFAS and concentrate them into foam, which can be skimmed. It is typically used for pretreatment or concentration, particularly for higher-strength sources. By reducing bulk PFAS loading ahead of adsorption, for example, FF can extend media life or shrink downstream system sizing.

On the destruction front, proper incineration of spent media is the primary commercially mature technology to destroy PFAS, but innovative and rapidly developing destruction technologies represent strong potential to eliminate long-term disposal liability by mineralizing PFAS. Advanced processes like supercritical water oxidation, hydrothermal alkaline treatment and electrochemical oxidation can break the carbon–fluorine bond under controlled conditions. Limitations of these novel technologies include energy intensity, capital cost and a relatively limited track record at full municipal drinking water scale. Due to the energy and capital expenses, destruction is most often applied following adsorption, membrane or foam concentrates rather than as a stand-alone treatment step.

Technology selection ultimately depends on source water chemistry, PFAS speciation and concentration, plant footprint, energy costs and residual disposal pathways. The most resilient approach is usually not a single technology but an integrated treatment train that balances capital and operating costs, regulatory compliance and long-term liability.

The Role of Testing

The PFAS NPDWR establishes two monitoring phases: initial monitoring and ongoing monitoring. While there has been no single federal start date, all community water systems and non-transient non-community water systems must have completed 12 months of initial monitoring prior to April 26, 2027. During that time, large systems (>10,000 people) and all surface water systems must collect four quarterly samples, and smaller groundwater systems must collect two samples spaced 5 to 7 months apart. To meet the deadline and account for laboratory capacity and scheduling constraints, utilities should already have started initial monitoring.

After the initial monitoring period, systems must then transition to ongoing monitoring, which begins with quarterly sampling regardless of system size, with potential reductions based on results. State primacy agencies may impose stricter requirements.

Proposed revisions to the PFAS NPDWR would offer extended compliance deadlines for meeting MCLs but not the monitoring timelines established in 2024.

Although compliance may be the primary goal of testing, results can provide critical data on PFAS concentrations and speciation, which directly inform treatment selection, media sizing and long-term system design.

All Carbon Is Not Created Equal

It is critical for engineers to recognize that activated carbon is not a commodity. Carbon performance can vary significantly due to differing feedstock material, activation processes, pore size distribution, surface characteristics and other factors, with significant impacts on lifecycle cost, vessel sizing and operational stability. Three attributes matter most: capacity, adsorption rate and purity.

Capacity determines how much PFAS a given carbon can remove before breakthrough. Higher-capacity media treat more bed volumes before exhaustion, reducing changeout frequency, labor, downtime and spent media disposal/regeneration. With landfills increasingly reluctant to accept PFAS-laden carbon, longer media life is an important risk management strategy.

Adsorption rate influences how quickly PFAS are removed within the empty bed contact time available. Faster kinetics can reduce vessel size, lower capital costs or increase throughput within an existing footprint.

Purity affects startup time and compliance with other drinking water standards. Some carbons can leach impurities like arsenic, increasing prewash volumes and complicating startup. Higher-purity products can reduce preconditioning time, wash water generation and related operational burden.

There are no universal performance standards that capture all these variables. Therefore, engineers should rely on site-specific evaluation tools such as Rapid Small-Scale Column Tests (RSSCT) or pilot studies to compare media under actual operating conditions. Modeling tools and case studies from comparable waters can provide directional insight, but they may not be substitutes for site validation.

Ultimately, carbon selection should be based on performance-adjusted cost, not purchase price alone. Lower-cost media that exhaust faster or require larger vessels can erase upfront savings through higher capital and operating expenses.

A Looming Activated Carbon Shortage

The surge in PFAS regulation is dramatically increasing demand for activated carbon. U.S. potable water carbon usage, historically on the order of hundreds of millions of pounds per year, is projected to skyrocket as systems turn to activated carbon to meet enforceable MCLs. With demand forecasted to triple by the end of the decade, purchasers are facing a potential supply shortage.

Much of the U.S. market relies on imported carbon or resellers sourcing from overseas manufacturers, which introduces exposure to tariffs, shipping disruptions and geopolitical instability. Water utilities do not typically maintain years of carbon inventory, so any disruption can quickly affect compliance operations.

For engineers and utilities, supply security now belongs in the same conversation as breakthrough curves and empty bed contact time. Evaluating supplier reliability, domestic manufacturing capacity and vertical integration are all parts of prudent risk management. Access to a stable and scalable activated carbon supply may prove just as important as treatment performance itself.

The Big Picture of PFAS Treatment

As more engineers wade into PFAS treatment waters, success will depend on a clear grasp of shifting regulations, the strengths and limits of available technologies and emerging supply chain constraints. Engineers who understand the full regulatory and lifecycle landscape will be better positioned to guide municipalities toward solutions that are technically sound, economically defensible and resilient over time.