For two years, many US property owners and industrial operators waited to see whether federal PFAS cleanup liability would survive legal challenge. In 2026, they got their answer.
On August 18, 2026, the D.C. Circuit unanimously denied industry petitions and upheld EPA’s designation of PFOA and PFOS as hazardous substances under CERCLA, the federal Superfund law. That ruling keeps the door open for cleanup orders and cost recovery claims tied to these two chemicals.
If your site ever used firefighting foam, metal plating, coatings, textiles treatments, or other PFAS sources, the question is no longer whether PFAS liability applies. The question is how much contamination sits in your soil and groundwater, and what the cleanup will cost.
What changed for PFAS in 2026
Three developments set the direction this year.
First, the CERCLA ruling. With the designation upheld, EPA keeps its ability to pursue response actions and cost recovery for PFOA and PFOS releases.
Second, drinking water standards. On May 18, EPA proposed keeping the 4 parts per trillion limits for PFOA and PFOS while rescinding limits for four other PFAS. The proposal would move the compliance date from April 2029 to April 2031 for systems that request more time. A two year extension does not change the target. Utilities still need to get PFOA and PFOS below 4 ppt.
Third, private lawsuits. In April 2026, a utility filed a CERCLA cost recovery action based on the PFOA and PFOS hazardous substance listings. Expect more claims as utilities spend money on treatment and look for the parties who caused the contamination.
These limits also matter beyond drinking water. The 2024 rule effectively set groundwater cleanup standards in states such as Michigan, Pennsylvania, and Wisconsin, and set CERCLA remedial cleanup criteria for PFOA and PFOS in groundwater.
Why PFAS sites start with hydrogeology
PFAS behave differently from fuels or solvents. They dissolve in water, resist breakdown, and travel long distances in groundwater. They also cling to soil, so a source area can feed a plume for decades.
You cannot design a cleanup without knowing where the contamination sits and where groundwater carries the chemicals. That is the job of hydrogeological consulting.
A typical investigation covers five areas.
Site history review. Records of foam use, fire training areas, process lines, spills, and waste disposal to locate likely source zones.
Soil sampling. Borings at and below source areas to measure PFAS concentrations by depth.
Monitoring wells. A well network to define the plume, measure groundwater flow direction, and track concentrations over time.
Aquifer testing. Pumping and slug tests to measure how fast water moves, which drives treatment design.
Conceptual site model. A clear picture of sources, pathways, and receptors such as supply wells, streams, or neighboring properties.
With this data, you can estimate liability, negotiate with regulators, and choose treatment that works.
Options for contaminated groundwater treatment
PFAS treatment has moved quickly, but the proven options remain few.
Pump and treat with granular activated carbon (GAC). Wells capture the plume and carbon vessels remove PFAS. GAC is the most widely used approach. Shorter chain PFAS break through faster, so monitoring and carbon changeout schedules matter.
Ion exchange resins. Resins can remove a wider range of PFAS in a smaller footprint, with higher material costs.
Reverse osmosis. Membranes remove PFAS well but produce a concentrated waste stream that needs disposal or destruction.
In situ sorbent barriers. Colloidal activated carbon injected into the aquifer can slow plume migration without pumping. Long term performance data is still building, so monitoring is essential.
The right contaminated groundwater treatment depends on plume size, PFAS mix, groundwater chemistry, and how fast you need results. Hydrogeological data guides each of those choices.
Options for soil remediation at PFAS sites
Contaminated soil keeps feeding groundwater until you deal with the source. Common soil remediation options include the following.
Excavation and off site disposal. Fast and certain, but costly, and disposal options for PFAS waste are limited in some states.
Stabilization. Mixing sorbents such as activated carbon or specialized amendments into soil to lock PFAS in place and reduce leaching.
Capping. A low permeability cover cuts rainfall infiltration through contaminated soil, slowing transfer to groundwater.
Thermal treatment. High temperature methods can destroy PFAS but use a lot of energy and remain expensive for large volumes.
Many sites combine soil remediation at the source with groundwater treatment downgradient.
How to choose a team for PFAS work
Ask these questions before you hire a firm.
Do you have PFAS sampling protocols that avoid cross contamination from field gear?
Have you built conceptual site models that regulators accepted?
Can you compare treatment options on cost, timeline, and long term risk?
Can you support negotiations with EPA or state agencies?
Will you set up monitoring that proves the remedy works?
Good hydrogeological consulting gives you defensible numbers early, so you control the conversation with regulators and buyers.
What you can do now
List every site you own or operate with a history of PFAS use. Review any past environmental reports for PFAS data. If none exists, commission a screening investigation at the highest risk site first. If you plan to buy or sell industrial property, add PFAS to your due diligence scope.
The legal path is now clearer. Owners who investigate early can plan cleanup on their own schedule. Owners who wait may face one set by a regulator or a court.
