PFHxS in drinking water
Also called perfluorohexanesulfonic acid.
A PFAS found in firefighting foam and carpet treatments.
Health: Linked to thyroid and liver effects and developmental effects. 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 63 systems serve about 4.3 million people.
From EPA's UCMR 5 testing, 2023–2025: every community system serving 3,300+ people and a sample of smaller ones.
Highest results
All 63 utilities on this site above the PFHxS limit, by state
Alaska: Barrow Utilities & Electric Cooperative, Inc.
Arizona: City of Tempe, Town of Payson, Marana Municipal – Marana, City of Globe
California: City of Fresno, City of Sacramento Main, California Water Service – Chico, City of Manteca, City of Pleasanton, City of Atwater, Big Bear City Community Services District, Crestline Village County Water District – Division 10, Running Springs Water District, Atascadero State Hospital Water System
Colorado: Widefield Water & Sanitation District
Florida: Emerald Coast Utilities Authority (ECUA), City of Ocala, City of Zephyrhills, Lake Panasoffkee Water Association
Georgia: Augusta-Richmond County Water System
Guam: Guam Waterworks Authority – Northern Water System
Idaho: Garden City Water and Sewer System
Illinois: North Park Public Water District
Indiana: South Bend Water Works
Kansas: Frusi Water Treatment Plant, City of Great Bend
Massachusetts: Sharon Water Dept, Duxbury Water Department
Michigan: Independence Township Water System
Minnesota: Woodbury Water System, Sauk Rapids Water System, Waite Park Water System
North Carolina: Bayleaf Master Water System, Brookwood Community Water System, Town of Nashville
New York: Yeshiva Farm Settlement Water System
Ohio: Wright-Patterson AFB Area B Public Water System
Oklahoma: Tri-County Rural Water District #2
Pennsylvania: Emmaus Borough Public Water, Beaver Borough Municipal Authority
Puerto Rico: PRASA – Ponce Urbano
Tennessee: Fort Campbell Water System
Texas: City of Fort Worth, City of Abilene, City of Haltom City, City of Boerne, Hawley Water Supply Corporation, Potosi Water Supply Corporation, Dyess Air Force Base Water System, Tanglewood on Texoma Water System
Utah: Hildale – Colorado City Water System
Washington: City of Moses Lake, Fairchild Air Force Base Water System, Quistorff Water System
Wisconsin: Pewaukee City Water and Sewer Utility, Saukville Waterworks, Prescott Waterworks
States with the most detections
- California: 146
- Texas: 145
- Florida: 105
- Pennsylvania: 58
- North Carolina: 55
- New Jersey: 50
- Wisconsin: 27
- Arizona: 26
- Washington: 26
- Ohio: 26
- Massachusetts: 24
- Alabama: 23
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 PFHxS 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 PFHxS from tap water?
See the filter guidance on this page: look for a product certified for PFHxS 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.