Short answer: yes. EPA says high-pressure membranes such as reverse osmosis are typically more than 90 percent effective at removing a wide range of PFAS, including shorter-chain compounds. At commercial scale the membrane is the easy part. The harder question is what happens to the roughly 20 percent of the feed water that leaves as a concentrated waste stream, and the federal rules behind all of this changed in May 2026.
If your facility draws from groundwater near an airfield, a fire training area or farmland that received biosolids, PFAS is a procurement question as well as a health one. This article covers where the rules stand, what RO does and does not do with PFAS, and what to ask before you buy a system. Every outside source is linked at the end.
Where the federal PFAS rules stand
On April 10, 2024, EPA finalized legally enforceable limits, called maximum contaminant levels or MCLs, for six PFAS in drinking water. On May 18, 2026, EPA announced two proposed rules that change that picture. One upholds the limits for PFOA and PFOS and gives water systems the option to request two more years, to 2031. The other would rescind the limits for PFHxS, PFNA, HFPO-DA (known as GenX) and the Hazard Index mixture that adds in PFBS. Both are proposals open for public comment, so check EPA’s page for the current status before you plan around either one.
| PFAS | 2024 final limit | May 2026 proposal |
|---|---|---|
| PFOA | 4.0 parts per trillion | Limit upheld, option to request until 2031 |
| PFOS | 4.0 parts per trillion | Limit upheld, option to request until 2031 |
| PFHxS | 10 parts per trillion | Proposed for rescission |
| PFNA | 10 parts per trillion | Proposed for rescission |
| HFPO-DA (GenX) | 10 parts per trillion | Proposed for rescission |
| Mixtures of PFHxS, PFNA, HFPO-DA and PFBS | Hazard Index of 1 | Proposed for rescission |
The limits bind public water systems. Whether your site counts as one depends on how many people it serves, so check with your state drinking water program. State limits can also differ from the federal ones.
What RO does well
EPA’s science staff describe nanofiltration and reverse osmosis as extremely effective at removing PFAS. Reverse osmosis membranes are tighter than nanofiltration membranes and reject all salts to a high degree. That is the same property that makes RO the standard answer for dissolved solids, and it is why one membrane stage can deal with PFAS, nitrate and salts together.
A percentage from a study is not a guarantee for your water. The same EPA page notes that results depend on the PFAS present and on the background organic matter and other contaminants in the water. Treat any rejection figure in a brochure as a starting point and ask for data that matches your analysis.
The part that decides your project: the concentrate
An RO system does not destroy PFAS. It separates them. EPA’s treatment page says that with high-pressure membranes about 80 percent of the feed water passes through as treated water and about 20 percent is retained as a high-strength concentrate, a waste stream that can be difficult to treat or dispose of, especially for a contaminant such as PFAS. EPA adds that the technology may be better suited to point-of-use treatment, where the volume is small.
For a commercial or industrial site, that sentence is the design brief. Before you choose a membrane, decide where the concentrate goes: hauled off site, treated further, or discharged under a permit your regulator has approved. Raising recovery cuts the volume of concentrate, but the PFAS in it become more concentrated and scaling risk goes up. Talk to your state environmental agency early, because the answer shapes the whole system.
RO is not the only option. EPA’s treatment overview also covers granular activated carbon and ion exchange, and which one fits depends on the PFAS you have, the organic matter in your water and how you plan to handle the waste. A site with other dissolved solids to remove often ends up with RO anyway.
Pretreatment still matters
PFAS-impacted groundwater often carries other contaminants that will foul a membrane long before PFAS becomes the limiting factor. Iron and manganese, hardness and suspended solids all need to be measured before the system is designed, and the pretreatment sized to match. A full water analysis is the first deliverable on any project, ahead of any model number. For the basics of what to measure, see our guide to RO water quality: TDS, pH and conductivity.
What to ask a manufacturer
- Which PFAS will the water be tested for, and does the lab report PFOA and PFOS down to 4 parts per trillion?
- Do you have performance data for water like mine, or only a general rejection figure?
- What is the recovery rate, and how much concentrate will the system produce each day?
- How would the concentrate be handled, and what has your team seen regulators accept?
- Which standards and certificates apply to this model, and can I have the paperwork for the exact model number?
The last question matters more than it looks. We cover how to read certification claims in how to choose a water treatment plant manufacturer.
Where AMPAC USA fits
AMPAC USA was founded in 1994 and builds commercial reverse osmosis systems and industrial RO plants from 6,000 to 100,000 GPD. We do not quote a PFAS removal figure without a water analysis, because the right answer depends on your water and on where the concentrate will go. Send us your daily flow, peak flow and a lab report through the quote form, or call (909) 548-4900. If you want a first look at flow and membrane sizing yourself, the RO system calculators are free.
Frequently asked questions
Does reverse osmosis remove PFAS?
Yes. EPA says high-pressure membranes, including reverse osmosis, are typically more than 90 percent effective at removing a wide range of PFAS, including shorter-chain compounds. Results depend on the specific PFAS and on the other contaminants in the water.
What happens to the PFAS that RO removes?
They stay in the concentrate stream. About 20 percent of the feed water typically leaves the system as concentrate, and EPA notes it can be difficult to treat or dispose of. Plan for it before you specify the system.
Has EPA changed the PFAS drinking water rule?
On May 18, 2026, EPA announced two proposed rules. One upholds the limits for PFOA and PFOS and offers an option to request until 2031 to comply. The other would rescind the limits for PFHxS, PFNA, HFPO-DA and the Hazard Index mixture. Both are proposals, so check EPA’s PFAS rule page for the current status.
Does the PFAS rule apply to my facility?
The enforceable limits apply to public water systems. Whether your site is one depends on how many people it serves, so ask your state drinking water program. If you are not a public water system, you may still choose to treat for PFAS because of contracts, insurance or the health of the people on site.
Bottom line
RO is a proven way to remove PFAS from water, and for sites that also need to remove dissolved solids it is often the natural choice. The deciding factors are your own water analysis and a plan for the concentrate. This article is general information, not legal or engineering advice for a specific site. If you are evaluating treatment for PFAS, contact our team at info@ampac1.com or (909) 548-4900.
Sources
- US EPA, Per- and Polyfluoroalkyl Substances (PFAS): Final PFAS National Primary Drinking Water Regulation, updated May 18, 2026
- US EPA Science Matters, Reducing PFAS in Drinking Water with Treatment Technologies, updated February 19, 2026
- US EPA, Overview of Drinking Water Treatment Technologies, updated March 23, 2026
AMPAC USA engineers custom water purification systems for commercial, industrial, and emergency applications — from 500 GPD to multi-million GPD. Trusted by municipalities, military, and industry worldwide.
