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Shortlist

Class of compounds

PFAS in drinking water

Also listed as PFOA / PFOS · PFOS · PFOA · Perfluorooctanoic acid

“Forever chemicals” from industry and firefighting foam. They break down very slowly and can build up in the body over time.

This page can’t tell you what’s in your tap water.
Only a test of water from your own tap can. Public-system results describe the system, not your home.
7 sources
01Check your water systemWater Check · system results, not your tap02Test your tapHow to get a reliable result03Treatment approachesWhat can reduce it at the tap
On this page · 10 sections
  1. 01Reference values
  2. 02Is it in my water?
  3. 03Where it comes from
  4. 04Testing
  5. 05Water filters
  6. 06Treatment
  7. 07Evidence
  8. 08Next steps
  9. 09Ask about PFAS
  10. 10References
Reference values

There’s no single reference number for “PFAS”.

Each value says what kind of reference it is, and they mean different things. A lower or missing number never means water is safe.

PFAS is a class of many chemicals. References and test results apply to named compounds.

PFAS: references held per named compound
CompoundKindValueStatus
PFOAEnforceable limit · MCL4 pptFinal rule · 2024
PFOSEnforceable limit · MCL4 pptFinal rule · 2024
PFHxSEnforceable limit · MCLNot shown while it’s under reconsiderationUnder reconsideration · 2024
PFNAEnforceable limit · MCLNot shown while it’s under reconsiderationUnder reconsideration · 2024
HFPO-DA (GenX)Enforceable limit · MCLNot shown while it’s under reconsiderationUnder reconsideration · 2024
Hazard Index (mixture rule)Enforceable limit · MCLNot shown while it’s under reconsiderationUnder reconsideration · 2024

A claim or a number for one compound never stands for “PFAS” as a whole.

Is it in my water?

Only a test of your own tap can tell.

Choose what you have. We’ll show what it can and can’t tell you.

If you haven’t tested
Nobody can tell without a measurement, including us.

Three things you can do, in this order.

Test water from your tapThis is the only way to know your level. Testing guidance ↓See what your system reportsSystem results aren’t a tap measurement. Open Water Check →On a private well?Public-system reports don’t cover wells. Open Well Water →
Where it comes from

Where it comes from

  1. PFAS have been used in industry and consumer products since the 1940s in nonstick cookware, food packaging, waterproof clothing, stain-resistant furniture, and firefighting foam.
  2. People can be exposed to PFAS in a variety of ways, and PFAS in drinking water can be a significant portion of a person's total PFAS exposure.
Why it matters
Exposure to PFAS may lead to health problems.
Testing

How to test your tap water for PFAS

Contact your local water provider to find out which PFAS, if any, are in your drinking water, or check EPA's database of PFAS water system test results or EPA's map-based PFAS Analytic Tools.

  1. 01Use a certified labA state-certified lab, or a kit that sends samples to one.
  2. 02Follow the sampling stepsHow and when you collect the water changes the result.
  3. 03Check the reportIt should state units and the detection limit.
Certified labNot sponsored
Use a state-certified labYour state keeps a list of labs certified for drinking water.

Choosing a filter for PFAS

None qualify
No products currently qualify for a PFAS pick here.

Nothing in our database has a PFAS claim for an exact configuration we can verify.

Find a fit in FinderRead treatment approaches
Treatment

How to reduce PFAS in water

Function: ReduceRemoving PFAS requires technologies that trap or separate these chemicals from water through adsorption, ion exchange, or membrane processes.
Reverse osmosisReverse osmosis forces water through an extremely thin barrier that separates PFAS chemicals from the water.Before you chooseClaims apply to the exact model and configuration tested.
Activated carbonActivated carbon filters use carbon to trap PFAS chemicals as water passes through them.Before you chooseClaims apply to the exact model and configuration tested.
Ion exchangeIon exchange resins are tiny beads that act like magnets to attract and hold PFAS from passing through the water system.Before you chooseClaims apply to the exact model and configuration tested.
Whole-house systems and point-of-use filters treat different water. A whole-house system treats water where it enters the home; a point-of-use filter treats the tap it’s installed on. Check which one a claim is for.
Evidence

What the evidence means

We keep evidence types apart. A result for one configuration never stands in for another, and we never average across types.

No product in our database holds a reduction record for PFAS yet.

How we read evidence →

Next steps

Take the next step

Match a system to your homeFinder asks about your home first. It suggests PFAS as a starting point, and nothing counts until you confirm it.
Ask about PFAS

Still have a question?

Answers come only from WaterDecoder’s reviewed sources and show citations. Ask can’t interpret your test result or choose a product. Don’t include personal details.

AI assistant

Ask about PFAS

Answers draw on cited public-health sources and the filters certified to reduce PFAS. Every source is linked, and if the sources don’t cover a question, the answer says so.

Questions to start with

Educational information from cited sources. Not medical or professional advice.

References

Where these facts come from

  1. 1Regulatory referenceEPA MCL (final 2024)
  2. 2Knowledge BaseOverview of Drinking Water Treatment TechnologiesUS EPA (SDWA program)
  3. 3Knowledge BaseReducing PFAS With Home Water FilterEPA
  4. 4Knowledge BaseTreatment Options for Removing PFAS from Drinking WaterUS EPA
  5. 5Knowledge BasePFAS in Drinking Water — regulatory trackerHarvard Environmental & Energy Law Program
  6. 6Knowledge BasePer- and Polyfluoroalkyl Substances (PFAS)US EPA
  7. 7Knowledge BaseHow PFAS Impacts Your HealthATSDR / CDC
  8. 8Knowledge BaseEPA'S Current Understanding Of PFASEPA

Written and maintained by WaterDecoder. A review date appears only once we have confirmed one.

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