PFAS ("forever chemicals")
11-Chloroeicosafluoro-3-oxaundecane-1-sulfonic acid (11Cl-PF3OUdS) in U.S. tap water
40 public water systems across 10 U.S. states report 11-Chloroeicosafluoro-3-oxaundecane-1-sulfonic acid (11Cl-PF3OUdS) in their annual Consumer Confidence Report. None currently sit at or above the federal limit.
See the PFAS Hotspots leaderboard → — every U.S. water system over EPA's finalized PFAS limit, ranked by severity, from the 2023–2025 UCMR5 lab dataset.
What it is
11-chloroeicosafluoro-3-oxaundecane-1-sulfonic acid, a chlorinated PFAS compound.
Why it's regulated
Monitored under EPA rules as part of broad PFAS surveillance.
Within the federal limit (38)
| Water system | Measured |
|---|---|
| Albuquerque, NM 2024 annual report | Not detected ng/L |
| Boonsboro Keedysville, MD 2024 annual report | Not detected ng/L |
| Brown Deer, WI 2023 annual report | Not detected ng/L |
| Butler, WI 2023 annual report | Not detected ng/L |
| Calvert Manor, MD 2024 annual report | Not detected |
| Chesapeake, VA 2023 annual report | Not detected ng/L |
| City of Mountain House — Mountain House, Ca, CA 2023 annual report | Not detected |
| Cotati, City of — Cotati, Ca, CA 2023 annual report | Not detected ng/L |
| Dearborn, MI 2024 annual report | Not detected ng/L |
| East Valley Water District — Highland, Ca, CA 2023 annual report | Not detected ng/L |
| Fallbrook Pud — Fallbrook, Ca, CA 2023 annual report | Not detected ng/L |
| Fillmore Water Dept — Fillmore, Ca, CA 2023 annual report | Not detected ng/L |
| Franklin, WI 2023 annual report | Not detected ng/L |
| Greendale, WI 2023 annual report | Not detected ng/L |
| Greenfield, WI 2023 annual report | Not detected ng/L |
| Hales Corners, WI 2023 annual report | Not detected ng/L |
| Los Angeles Cwwd 36-val Verde — Alhambra, Ca, CA 2023 annual report | Not detected ng/L |
| Menomonee Falls, WI 2023 annual report | Not detected ng/L |
| Mequon, WI 2023 annual report | Not detected ng/L |
| Milwaukee, WI 2023 annual report | Not detected ng/L |
| Montecito Water Dist — Santa Barbara, Ca, CA 2023 annual report | Not detected ng/L |
| New Berlin, WI 2023 annual report | Not detected ng/L |
| Paradise Ranch Mhp — Beverly Hills, Ca, CA 2023 annual report | Not detected ng/L |
| Pasadena, CA 2023 annual report | Not detected ng/L |
| Salem, OR 2023 annual report | Not detected |
| Santa Clarita, CA 2024 annual report | Not detected ng/L |
| Shorewood, WI 2023 annual report | Not detected ng/L |
| South Tahoe Pud - Main — South Lake Tahoe, Ca, CA 2023 annual report | Not detected ng/L |
| St. Francis, WI 2023 annual report | Not detected ng/L |
| Thiensville, WI 2023 annual report | Not detected ng/L |
| Tracy, CA 2024 annual report | Not detected |
| Ventura Cwwd No. 1 - Moorpark — Moorpark, Ca, CA 2023 annual report | Not detected |
| Vineyard Ave Estates Mwc — Oxnard, Ca, CA 2022 annual report | Not detected ng/L |
| Waukesha, WI 2023 annual report | Not detected ng/L |
| Wauwatosa, WI 2023 annual report | Not detected ng/L |
| West Allis, WI 2023 annual report | Not detected ng/L |
| West Valley City, UT 2024 annual report | Not detected ng/L |
| Wilmington, NC 2024 annual report | Not detected ng/L |
Frequently asked
+What is 11-Chloroeicosafluoro-3-oxaundecane-1-sulfonic acid (11Cl-PF3OUdS)?
11-chloroeicosafluoro-3-oxaundecane-1-sulfonic acid, a chlorinated PFAS compound. Monitored under EPA rules as part of broad PFAS surveillance.
+What is the federal limit for 11-Chloroeicosafluoro-3-oxaundecane-1-sulfonic acid (11Cl-PF3OUdS) in drinking water?
The federal NL for 11-Chloroeicosafluoro-3-oxaundecane-1-sulfonic acid (11Cl-PF3OUdS) is 0.005 . 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 11-Chloroeicosafluoro-3-oxaundecane-1-sulfonic acid (11Cl-PF3OUdS) over the federal limit?
Zero of the 40 public water systems in The Water Map dataset currently report 11-Chloroeicosafluoro-3-oxaundecane-1-sulfonic acid (11Cl-PF3OUdS) at or above its federal limit.
+How can I check if 11-Chloroeicosafluoro-3-oxaundecane-1-sulfonic acid (11Cl-PF3OUdS) 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 11-Chloroeicosafluoro-3-oxaundecane-1-sulfonic acid (11Cl-PF3OUdS).
See 11-Chloroeicosafluoro-3-oxaundecane-1-sulfonic acid (11Cl-PF3OUdS) on the map
Color-coded by status across the whole country.
Open the map →