HFPO-DA (GenX) in drinking water
Also called GenX chemicals, hexafluoropropylene oxide dimer acid.
The replacement for PFOA in making Teflon. Known for contamination of the Cape Fear River in North Carolina.
Health: Linked to liver, kidney and immune effects in animal studies. Also part of the Hazard Index.
EPA proposed in May 2026 to rescind this limit. The proposal is not final. The April 2024 limit stays on the books until a final rule says otherwise.
Across the US
Those 8 systems serve about 190,246 people.
From EPA's UCMR 5 testing, 2023–2025: every community system serving 3,300+ people and a sample of smaller ones.
Highest results
| Water system | People | Highest average |
|---|---|---|
| City of Abbeville | 5,650 | 81.4 ppt |
| Greenwood Commission of Public Works | 52,022 | 62.8 ppt |
| City of Belton | 6,762 | 41.9 ppt |
| Laurens County Water & Sewer Commission | 44,866 | 35.1 ppt |
| Robeson County Water System | 67,970 | 33.5 ppt |
| Town of Honea Path | 4,386 | 25.5 ppt |
| Saluda Commission of Public Works | 3,390 | 25.3 ppt |
| Donalds-Due West Water & Sewer Authority | 5,200 | 16.4 ppt |
| Town of Ware Shoals | 3,174 | 12.8 ppt |
| Perth Amboy Water Department | 52,328 | 11.9 ppt |
| City of Newberry | 10,810 | 8.65 ppt |
| BGWC I-20 | 7,435 | 8.53 ppt |
| Joint Municipal WSC | 54,868 | 8.33 ppt |
| Newberry County Water & Sewer Authority | 11,157 | 8.33 ppt |
| City of Columbia | 354,068 | 8.05 ppt |
| City of West Columbia | 34,028 | 7.65 ppt |
| Town of Lexington | 24,284 | 7.15 ppt |
| Saluda County Water & Sewer Authority | 5,060 | 7.13 ppt |
| The Cape Master System | 11,587 | 7 ppt |
| Bladen County Water District – East Bladen | 4,310 | 6.8 ppt |
| Amicks Ferry Water System | 3,937 | 6.58 ppt |
| Big Sandy Water District | 13,044 | 6.25 ppt |
| City of Clinton | 8,938 | 4.85 ppt |
| City of Cayce | 17,460 | 4.75 ppt |
| Ironton Water System | 11,129 | 4.38 ppt |
States with the most detections
- South Carolina: 24
- North Carolina: 7
- Kentucky: 3
- Ohio: 3
- New Jersey: 2
- Indiana: 2
- Virginia: 2
- West Virginia: 1
- Michigan: 1
- Louisiana: 1
Sources
The limits, health goals and health effects on this page come from these EPA sources. The results come from EPA's monitoring data for each water system.
- EPA: Per- and polyfluoroalkyl substances (PFAS) drinking water rule
- EPA: Fifth Unregulated Contaminant Monitoring Rule (UCMR 5)
- EPA: UCMR occurrence data (the test results)
This page summarizes public regulatory information. It is not medical advice. How we source and check this site.
Questions
What is the safe level of HFPO-DA (GenX) in drinking water?
The federal legal limit (MCL) is 10 ppt. EPA's health goal (MCLG), the level with no known risk, is 10 ppt. EPA proposed in May 2026 to rescind this limit. The proposal is not final. The April 2024 limit stays on the books until a final rule says otherwise.
How do I remove HFPO-DA (GenX) from tap water?
See the filter guidance on this page: look for a product certified for HFPO-DA (GenX) specifically, and check the claim in NSF's certified product listings.
Source: U.S. EPA drinking water records and PFAS testing (UCMR 5). How we read the data.