PFAS ("forever chemicals")
Perfluorobutanesulfonic acid in U.S. tap water
278 public water systems across 31 U.S. states report Perfluorobutanesulfonic acid 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
Perfluorobutanesulfonic acid, a shorter-chain PFAS 'forever chemical.'
Why it's regulated
Has no standalone limit but is part of the EPA PFAS Hazard Index that limits PFAS in combination.
Within the federal limit (53)
| Water system | Measured |
|---|---|
| Albuquerque, NM 2024 annual report | Not detected ng/L |
| Anchorage, AK 2024 annual report | Not detected ng/L |
| Backbone Mountain Boys Camp, MD 2024 annual report | Not detected ng/L |
| Bellflower Municipal Water System — Rosemead, Ca, CA 2023 annual report | Not detected |
| Brown Deer, WI 2023 annual report | Not detected ng/L |
| Butler, WI 2023 annual report | Not detected ng/L |
| Cal American Water Co — Rosemead, Ca, CA 2023 annual report | Not detected |
| Cal/am Water Company - Baldwin Hills — Rosemead, Ca, CA 2023 annual report | Not detected |
| Calvert Manor, MD 2024 annual report | Not detected |
| Carpinteria Valley Water District — Carpinteria, Ca, CA 2023 annual report | Not detected ng/L |
| Cheltenham Youth Facility, MD 2024 annual report | Not detected ng/L |
| Chesapeake, VA 2023 annual report | Not detected ng/L |
| Cincinnati, OH 2024 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 |
| Covina Irrigating Co. — West Covina, Ca, CA 2023 annual report | Not detected ng/L |
| Dearborn, MI 2024 annual report | Not detected ng/L |
| Eastern Correctional Institute, MD 2024 annual report | Not detected ng/L |
| El Cajon, CA 2024 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 |
| Foothill Municipal Water Dist. — La Canada Flintridge, Ca, CA 2023 annual report | Not detected ng/L |
| Franklin, WI 2023 annual report | Not detected ng/L |
| Freedom District, MD 2024 annual report | Not detected ng/L |
| Grand Rapids, MI 2025 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 |
| Helix Water District — La Mesa, Ca, CA 2023 annual report | Not detected ng/L |
| Lompoc-city Water Utility Div — Lompoc, 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 |
| North Marin Water District — Novato, Ca, CA 2023 annual report | Not detected ng/L |
| Pasadena, CA 2023 annual report | Not detected ng/L |
| Sacramento Suburban Water District — Sacramento, Ca, CA 2023 annual report | Not detected ng/L |
| Salem, OR 2023 annual report | Not detected ng/L |
| San Joaquin County - Lincoln Village — Stockton, Ca, CA 2023 annual report | Not detected ng/L |
| Santa Rosa, 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 |
| Suffolk, VA 2024 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 |
| Waukesha, WI 2023 annual report | Not detected ng/L |
| Wauwatosa, WI 2023 annual report | Not detected ng/L |
Showing 50 of 53. The full list is in the JSON API.
Frequently asked
+What is Perfluorobutanesulfonic acid?
Perfluorobutanesulfonic acid, a shorter-chain PFAS 'forever chemical.' Has no standalone limit but is part of the EPA PFAS Hazard Index that limits PFAS in combination.
+What is the federal limit for Perfluorobutanesulfonic acid in drinking water?
The federal Public health goal for Perfluorobutanesulfonic acid is 2 ng/L. 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 Perfluorobutanesulfonic acid over the federal limit?
Zero of the 278 public water systems in The Water Map dataset currently report Perfluorobutanesulfonic acid at or above its federal limit.
+How can I check if Perfluorobutanesulfonic 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 Perfluorobutanesulfonic acid.
See Perfluorobutanesulfonic acid on the map
Color-coded by status across the whole country.
Open the map →