PFAS · CAS 62037-80-3
GenX (HFPO-DA) in Tap Water
GenX (HFPO-DA) is a newer PFAS "forever chemical" introduced as a replacement for PFOA. It is now federally regulated both on its own and as part of a PFAS hazard index.
Substance identity
- Scientific name
- Hexafluoropropylene oxide dimer acid (HFPO-DA)
- Family
- PFAS
- CAS number
- 62037-80-3
This guide explains the compound. Only a water-system record or household test can tell you whether it appears in your water.
- Federal reference
- 10 ng/L (MCL); MCLG of 10 ng/LEnforceable maximum contaminant level
- Health-based goal
- 10 ng/L individual MCL; also limited via a combined PFAS hazard indexUS EPA PFAS National Primary Drinking Water Regulation (2024)
- Measurement context
- Stated in the recordUCMR5 monitored a broad list of PFAS nationally, but PurityMap’s current dataset ingests per-system occurrence only for PFOA, PFOS, and PFHxS. PurityMap does not yet publish a per-system measured value for GenX (HFPO-DA); this page is a reference explainer. To learn what is in your own water, check your utility’s Consumer Confidence Report (CCR) or use a certified home test.
- Cities on record
- None yetUS cities in PurityMap's published record where GenX (HFPO-DA) appears
A reference is a published threshold, not a safety line drawn by PurityMap. Where a result sits against it is a finding; whether that constitutes a violation is a separately published compliance field.
What is GenX (HFPO-DA)?
GenX (HFPO-DA) is a newer PFAS "forever chemical" introduced as a replacement for PFOA. It is now federally regulated both on its own and as part of a PFAS hazard index.
Where GenX (HFPO-DA) comes from
Fluoropolymer manufacturing discharge; persistent and mobile in water.
- Fluoropolymer / chemical manufacturing discharge
Most affected: Infants, pregnant people, and immunocompromised individuals.
How GenX (HFPO-DA) is measured
UCMR5 monitored a broad list of PFAS nationally, but PurityMap’s current dataset ingests per-system occurrence only for PFOA, PFOS, and PFHxS. PurityMap does not yet publish a per-system measured value for GenX (HFPO-DA); this page is a reference explainer. To learn what is in your own water, check your utility’s Consumer Confidence Report (CCR) or use a certified home test.
Why context mattersHow PurityMap reads a GenX (HFPO-DA) result
Evidence exceeds a reference level. Used sparingly and only when warranted.
This substance was found in the monitoring record. Being present is not the same as being above a reference level, and this signal does not say which.
Somebody looked and the laboratory reported nothing above its reporting limit. This is a result, and it is not the same as nobody looking.
No sampling for this substance has been reported for this system. Nothing is known either way, and an empty row is not a clean one.
Where the numbers come from
- A laboratory result for one sampling point
Collected under a monitoring programme, analysed by an approved method, and reported with its own detection limits.
- Read against a published reference
The reference comes from the regulator, with its own effective date. PurityMap does not set thresholds and does not adjust them.
- Attached to a system's Water Profile
Where it contributes to the published assessment alongside the evidence quality of the record it came from.
The full evidence chain →
Where GenX (HFPO-DA) is found across the U.S.
These are the places in PurityMap’s published record where GenX (HFPO-DA) appears on a water system’s monitoring results. It reflects the systems and sampling we track, not a national prevalence estimate.
PurityMap has no city on record with GenX (HFPO-DA) on its monitoring results yet. This fills in as monitoring data is published — a substance that was never tested is shown as pending, never as a pass.
Treatment capability, if a finding establishes a need
The formats that commonly hold a verified reduction claim for GenX (HFPO-DA) are Reverse osmosis, Activated carbon (GAC), Anion exchange. Holding the format is not holding the claim — the certification record is what is checked.
Boiling does not remove a dissolved chemical compound and can concentrate it. Many pitcher and refrigerator filters carry no verified claim for a compound like this at all.
Whether a system-level measurement or a household-tap measurement is the relevant scope depends on how the compound enters the water — a published characteristic of the record, not an assumption drawn here.
A finding establishes the need, the need names the capability, the capability requires a verified certification. No product appears before that sequence completes.
Filter Finder →Frequently asked questions
What is GenX (HFPO-DA)?
GenX (HFPO-DA) is a newer PFAS "forever chemical" introduced as a replacement for PFOA. It is now federally regulated both on its own and as part of a PFAS hazard index.
What is the limit for GenX (HFPO-DA) in drinking water?
The enforceable federal limit is 10 ng/L (MCL); MCLG of 10 ng/L. The health-based goal is 10 ng/L individual MCL; also limited via a combined PFAS hazard index. PurityMap reads every measurement against its stated benchmark and never sets its own.
Where does GenX (HFPO-DA) in tap water come from?
Fluoropolymer / chemical manufacturing discharge.
Why does GenX (HFPO-DA) matter?
GenX is associated in studies with liver, kidney, immune, and developmental effects. It was introduced as a replacement for PFOA, but it is likewise persistent, which is why the EPA regulates it directly and within the PFAS hazard index.
How do you remove GenX (HFPO-DA) from water?
Treatment technologies commonly certified to reduce GenX (HFPO-DA) include Reverse osmosis, Activated carbon (GAC), Anion exchange. Match the exact certified claim to your water before buying — holding a format is not the same as holding the claim.
Sources and methodology
Reference values on this page come from the governed contaminant record. Local occurrence claims stay on the linked water-system evidence pages, where sampling scope, period and source remain visible.
How PurityMap analyzes water data →