EPA legal limit
10 ppt
Maximum Contaminant Level
EWG health guideline
1 ppt
Science-based, stricter target
Health effects
HFPO-DA is associated with liver toxicity, kidney effects, immune disruption, and developmental harm in animal studies. It does not bioaccumulate as readily as long-chain PFAS but is highly persistent in water. It crosses the placental barrier. The EPA classifies it as having "suggestive evidence of carcinogenic potential."
Where it comes from
Industrial manufacturing of fluoropolymers (Teflon and similar non-stick coatings). Major documented contamination sources include DuPont/Chemours plants near Wilmington, North Carolina (Cape Fear River) and Parkersburg, West Virginia. Also identified near other fluoropolymer production facilities.
How it's regulated
EPA MCL: 10 ppt (effective April 2024). Note: EPA announced in May 2025 a proposal to rescind the HFPO-DA MCL while retaining the PFOA/PFOS MCLs. The 10 ppt limit remains in effect as of 2025 but is under regulatory review. Previously tracked under EPA's 2022 Lifetime Health Advisory of 10 ppt.
The EPA vs EWG gap
The legal limit (10 ppt) is 10× higher than the EWG health guideline (1 ppt). Water can be legally compliant while still exceeding the science-based threshold.
How to filter hfpo-da / genx
Not all filters address hfpo-da / genx. Look for independently certified filters — NSF International certification means the removal claim has been independently verified.
Frequently asked questions
What is hfpo-da / genx?
HFPO-DA (also known as GenX) is a short-chain PFAS compound used as a replacement for PFOA in the manufacture of non-stick coatings and fluoropolymers. It is structurally different from most other PFAS in having an ether linkage. Contamination has been documented near fluoropolymer manufacturing plants, most notably the Cape Fear River basin in North Carolina.
What are the health effects of hfpo-da / genx?
HFPO-DA is associated with liver toxicity, kidney effects, immune disruption, and developmental harm in animal studies. It does not bioaccumulate as readily as long-chain PFAS but is highly persistent in water. It crosses the placental barrier. The EPA classifies it as having "suggestive evidence of carcinogenic potential."
Is hfpo-da / genx regulated in drinking water?
EPA MCL: 10 ppt (effective April 2024). Note: EPA announced in May 2025 a proposal to rescind the HFPO-DA MCL while retaining the PFOA/PFOS MCLs. The 10 ppt limit remains in effect as of 2025 but is under regulatory review. Previously tracked under EPA's 2022 Lifetime Health Advisory of 10 ppt.
Where does hfpo-da / genx come from?
Industrial manufacturing of fluoropolymers (Teflon and similar non-stick coatings). Major documented contamination sources include DuPont/Chemours plants near Wilmington, North Carolina (Cape Fear River) and Parkersburg, West Virginia. Also identified near other fluoropolymer production facilities.
How do I remove hfpo-da / genx from tap water?
The most effective methods for removing hfpo-da / genx are: Reverse osmosis (RO), NSF 58 certified RO system, Activated carbon block filter. Look for NSF-certified systems — independent certification confirms removal claims have been verified.
Is hfpo-da / genx in your water?
Enter your ZIP code to see the measured level in your specific utility.