PFAS ("forever chemicals")
Hexafluoropropylene oxide dimer acid in U.S. tap water
61 public water systems across 19 U.S. states report Hexafluoropropylene oxide dimer acid in their annual Consumer Confidence Report. 2 sit at or above the federal limit.
What it is
HFPO-DA ('GenX chemicals'), a newer-generation PFAS replacement compound.
Why it's regulated
Regulated by the EPA at 10 parts per trillion and included in the PFAS Hazard Index.
At or above the federal limit (2)
| Water system | Measured | vs. limit |
|---|---|---|
| Boonsboro Keedysville, MD 2024 annual report | 13252–6 | 1.2× the limit |
| Pomona, CA 2024 annual report | 5 ng/L | 1.0× the limit |
Within the federal limit (48)
| Water system | Measured |
|---|---|
| New Orleans, LA 2024 annual report | 0–5.4 ng/L |
| Albuquerque, NM 2024 annual report | Not detected |
| Anchorage, AK 2024 annual report | Not detected ng/L |
| Brown Deer, WI 2024 annual report | Not detected ug/L |
| Butler, WI 2024 annual report | Not detected ug/L |
| Calvert Manor, MD 2024 annual report | Not detected |
| Chandler, AZ 2024 annual report | 0 ng/L |
| City of Baltimore, MD 2024 annual report | Not detected |
| Dallas, TX 2024 annual report | Not detected ng/L |
| Dearborn, MI 2024 annual report | Not detected ug/L |
| El Cajon, CA 2024 annual report | Not detected ng/L |
| Franklin, WI 2024 annual report | Not detected ug/L |
| Glendale, AZ 2024 annual report | Not detected ng/L |
| Grand Rapids, MI 2025 annual report | Not detected ng/L |
| Greendale, WI 2024 annual report | Not detected ug/L |
| Greenfield, WI 2024 annual report | Not detected ug/L |
| Hales Corners, WI 2024 annual report | Not detected ug/L |
| Louisville, KY 2024 annual report | 0 |
| Lubbock, TX 2024 annual report | Not detected ng/L |
| Menomonee Falls, WI 2024 annual report | Not detected ug/L |
| Mequon, WI 2024 annual report | Not detected ug/L |
| Milwaukee, WI 2024 annual report | Not detected ug/L |
| New Berlin, WI 2024 annual report | Not detected ug/L |
| Oxnard, CA 2024 annual report | Not detected |
| Pasadena, CA 2023 annual report | Not detected ug/L |
| Philadelphia, PA 2023 annual report | 0 |
| Raleigh, NC 2024 annual report | Not detected |
| Rockville, MD 2024 annual report | 0 |
| Salem, OR 2023 annual report | Not detected ug/L |
| Santa Clarita, CA 2024 annual report | Not detected ug/L |
| Santa Rosa, CA 2024 annual report | Not detected ng/L |
| Shorewood, WI 2024 annual report | Not detected ug/L |
| St. Francis, WI 2024 annual report | Not detected ug/L |
| Suffolk, VA 2024 annual report | Not detected ng/L |
| Tempe, AZ 2024 annual report | Not detected ng/L |
| Thiensville, WI 2024 annual report | Not detected ug/L |
| Town of Garner, NC 2024 annual report | Not detected |
| Town of Knightdale, NC 2024 annual report | Not detected |
| Town of Rolesville, NC 2024 annual report | Not detected |
| Town of Wake Forest, NC 2024 annual report | Not detected |
| Town of Wendell, NC 2024 annual report | Not detected |
| Town of Zebulon, NC 2024 annual report | Not detected |
| Tracy, CA 2024 annual report | Not detected |
| Vancouver, WA 2024 annual report | Not detected |
| Waukesha, WI 2024 annual report | Not detected ug/L |
| Wauwatosa, WI 2024 annual report | Not detected ug/L |
| West Allis, WI 2024 annual report | Not detected ug/L |
| West Valley City, UT 2024 annual report | Not detected ug/L |
Frequently asked
+What is Hexafluoropropylene oxide dimer acid?
HFPO-DA ('GenX chemicals'), a newer-generation PFAS replacement compound. Regulated by the EPA at 10 parts per trillion and included in the PFAS Hazard Index.
+What is the federal limit for Hexafluoropropylene oxide dimer acid in drinking water?
The federal MCL for Hexafluoropropylene oxide dimer acid is 1.8 . The EPA enforces this against the regulated reporting statistic (typically a running annual average or 90th percentile), not a single-sample spike.
+How many U.S. water systems have Hexafluoropropylene oxide dimer acid over the federal limit?
2 of the 61 public water systems on The Water Map report Hexafluoropropylene oxide dimer acid at or above its federal limit, spanning 19 U.S. states. The full list is on this page.
+How can I check if Hexafluoropropylene oxide dimer acid is in my city's tap water?
Search your city on The Water Map (https://www.thewatermap.com/) or browse the list on this page. Every U.S. public water utility is required to publish an annual Consumer Confidence Report that lists every contaminant it measured, including Hexafluoropropylene oxide dimer acid.
See Hexafluoropropylene oxide dimer acid on the map
Color-coded by status across the whole country.
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