PFAS ("forever chemicals")
PFOS in U.S. tap water
327 public water systems across 31 U.S. states report PFOS in their annual Consumer Confidence Report. 148 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.
327
systems measuring
148
over the limit
31
states represented
What it is
Perfluorooctanesulfonic acid, a PFAS 'forever chemical' once used in firefighting foam and coatings.
Why it's regulated
Linked to cancer, thyroid disease, and immune effects; the EPA set an enforceable limit of 4 parts per trillion.
Federal limit4 ng/L· MCL
At or above the federal limit (148)
| Water system | Measured | vs. limit |
|---|---|---|
| Home Gardens County Wd — Corona, Ca, CA 2022 annual report | 0–240 ng/L | 60.0× the limit |
| Bellflower - Somerset Mwc — Bellflower, Ca, CA 2022 annual report | 115 ng/L | 28.8× the limit |
| Valley of the Moon Water District — El Verano, Ca, CA 2023 annual report | 80 ng/L | 20.0× the limit |
| Montebello Land & Water Co. — Montebello, Ca, CA 2023 annual report | 60 ng/L | 15.0× the limit |
| Hesperia, CA 2024 annual report | 0–50.3 ng/L | 12.6× the limit |
| Montebello Land & Water Co. — Montebello, Ca, CA 2022 annual report | 48 ng/L | 12.0× the limit |
| Montebello Land & Water Co. — Montebello, Ca, CA 2020 annual report | 46 ng/L | 11.5× the limit |
| Hialeah, FL 2023 annual report | 0–38 ng/L | 9.5× the limit |
| Boh Nak Mhp, MD 2024 annual report | 37 ng/L | 9.3× the limit |
| City of Hialeah, FL 2023 annual report | 15–35 ng/L | 8.8× the limit |
| City of North Miami Beach, FL 2023 annual report | 15–35 ng/L | 8.8× the limit |
| Miami Dade, FL 2023 annual report | 15–35 ng/L | 8.8× the limit |
| Chula Vista Sweetwater, CA 2024 annual report | 0–33 ng/L | 8.3× the limit |
| Sweetwater Authority — Chula Vista, Ca, CA 2023 annual report | 0–33 ng/L | 8.3× the limit |
| Atascadero Mutual Water Co — Atascadero, Ca, CA 2023 annual report | 32 ng/L | 8.0× the limit |
| Orchard Dale Water District — Whittier, Ca, CA 2022 annual report | 17–32 ng/L | 8.0× the limit |
| Gswc - Hollydale — Anaheim, Ca, CA 2021 annual report | 31 ng/L | 7.8× the limit |
| South Montebello Irrigation Dist. — Montebello, Ca, CA 2020 annual report | 30.75 ng/L | 7.7× the limit |
| South Montebello Irrigation Dist. — Montebello, Ca, CA 2022 annual report | 30 ng/L | 7.5× the limit |
| Downey, CA 2024 annual report | 29.5 ng/L | 7.4× the limit |
| Downey - City, Water Dept. — Downey, Ca, CA 2023 annual report | 29.5 ng/L | 7.4× the limit |
| Orchard Dale Water District — Whittier, Ca, CA 2021 annual report | 29.2 ng/L | 7.3× the limit |
| Liberty Utilities - Bellflower-norwalk — Downey, Ca, CA 2023 annual report | 28 ng/L | 7.0× the limit |
| City of Pleasanton — Pleasanton, Ca, CA 2023 annual report | 27.2 ng/L | 6.8× the limit |
| Whittier-city, Water Dept. — Whittier, Ca, CA 2020 annual report | 12–26 ng/L | 6.5× the limit |
| Abilene, TX 2024 annual report | 25.6 ng/L | 6.4× the limit |
| City of Bell Gardens — Downey, Ca, CA 2023 annual report | 24.8 ng/L | 6.2× the limit |
| Pico Wd — Pico Rivera, Ca, CA 2021 annual report | 24.79 ng/L | 6.2× the limit |
| Pico Wd — Pico Rivera, Ca, CA 2020 annual report | 24.3 ng/L | 6.1× the limit |
| Tract 349 Mutual Water Co. — Cudahy, Ca, CA 2023 annual report | 24.1 ng/L | 6.0× the limit |
| Vancouver, WA 2024 annual report | 0–23.1 ng/L | 5.8× the limit |
| City of Lathrop — Lathrop, Ca, CA 2023 annual report | 0–23 ng/L | 5.8× the limit |
| South Montebello Irrigation Dist. — Montebello, Ca, CA 2021 annual report | 23 ng/L | 5.8× the limit |
| City of Bell Gardens — Downey, Ca, CA 2022 annual report | 21.4 ng/L | 5.3× the limit |
| Norwalk - City, Water Dept. — Norwalk, Ca, CA 2022 annual report | 21.1 ng/L | 5.3× the limit |
| Pico Rivera - City, Water Dept. — Pico Rivera, Ca, CA 2023 annual report | 20.6 ng/L | 5.2× the limit |
| Fayetteville, NC 2024 annual report | 20.18 ng/L | 5.0× the limit |
| Commerce-city, Water Dept. — San Jose, Ca, CA 2021 annual report | 20 ng/L | 5.0× the limit |
| Grand Prairie, TX 2024 annual report | 20 ng/L | 5.0× the limit |
| Reno, NV 2024 annual report | 20 ng/L | 5.0× the limit |
| Pico Wd — Pico Rivera, Ca, CA 2022 annual report | 19.75 ng/L | 4.9× the limit |
| Pico Wd — Pico Rivera, Ca, CA 2023 annual report | 19.73 ng/L | 4.9× the limit |
| Atascadero State Hospital — Atascadero, Ca, CA 2022 annual report | 18.65 ng/L | 4.7× the limit |
| Greensboro, NC 2024 annual report | 18.1 ng/L | 4.5× the limit |
| Pomona, CA 2024 annual report | 0–18 ng/L | 4.5× the limit |
| Pico Rivera - City, Water Dept. — Pico Rivera, Ca, CA 2022 annual report | 17.8 ng/L | 4.5× the limit |
| Lakewood - City, Water Dept. — Lakewood, Ca, CA 2023 annual report | 17 ng/L | 4.3× the limit |
| Santa Fe Springs - City, Water Dept. — Santa Fe Springs, Ca, CA 2020 annual report | 17 ng/L | 4.3× the limit |
| South Gate-city, Water Dept. — South Gate, Ca, CA 2023 annual report | 16.4 ng/L | 4.1× the limit |
| Gswc - Hollydale — Anaheim, Ca, CA 2020 annual report | 16 ng/L | 4.0× the limit |
| South Montebello Irrigation Dist. — Montebello, Ca, CA 2023 annual report | 15 ng/L | 3.8× the limit |
| Suburban Water Systems-la Mirada — Covina, Ca, CA 2020 annual report | 15 ng/L | 3.8× the limit |
| City of Arcadia — Arcadia, Ca, CA 2023 annual report | 0–14 ng/L | 3.5× the limit |
| City of Arcadia — Arcadia, Ca, CA 2021 annual report | 0–14 ng/L | 3.5× the limit |
| Riverside Highland Water Company — Grand Terrace, Ca, CA 2023 annual report | 0–14 ng/L | 3.5× the limit |
| Santa Fe Springs - City, Water Dept. — Santa Fe Springs, Ca, CA 2023 annual report | 14 ng/L | 3.5× the limit |
| Whittier-city, Water Dept. — Whittier, Ca, CA 2023 annual report | 0–14 ng/L | 3.5× the limit |
| Suburban Water Systems-la Mirada — Covina, Ca, CA 2021 annual report | 13.38 ng/L | 3.3× the limit |
| Colton, City of — Colton, Ca, CA 2023 annual report | 13.3 ng/L | 3.3× the limit |
| Terrace Water Company — Colton, Ca, CA 2023 annual report | 13.3 ng/L | 3.3× the limit |
| Bellflower Municipal Water System — Rosemead, Ca, CA 2022 annual report | 13 ng/L | 3.3× the limit |
| Glendale, CA 2024 annual report | 13 ng/L | 3.3× the limit |
| Bellflower - Somerset Mwc — Bellflower, Ca, CA 2023 annual report | 12.9 ng/L | 3.2× the limit |
| Avondale, AZ 2024 annual report | 0–12 ng/L | 3.0× the limit |
| Bellflower Municipal Water System — Rosemead, Ca, CA 2023 annual report | 12 ng/L | 3.0× the limit |
| City of Arcadia — Arcadia, Ca, CA 2022 annual report | 0–12 ng/L | 3.0× the limit |
| City of Arcadia — Arcadia, Ca, CA 2020 annual report | 0–12 ng/L | 3.0× the limit |
| Whittier-city, Water Dept. — Whittier, Ca, CA 2021 annual report | 6.8–12 ng/L | 3.0× the limit |
| Suburban Water Systems-whittier — Covina, Ca, CA 2023 annual report | 11.8 ng/L | 3.0× the limit |
| Maywood Mutual Water Co. #3 — Maywood, Ca, CA 2023 annual report | 11.4 ng/L | 2.9× the limit |
| Del Rio Mutual — El Monte, Ca, CA 2023 annual report | 11.27 ng/L | 2.8× the limit |
| City of Redding — Redding, Ca, CA 2023 annual report | 11.1 ng/L | 2.8× the limit |
| Santa Fe Springs - City, Water Dept. — Santa Fe Springs, Ca, CA 2021 annual report | 11 ng/L | 2.8× the limit |
| Whittier-city, Water Dept. — Whittier, Ca, CA 2022 annual report | 5.7–11 ng/L | 2.8× the limit |
| Suburban Water Systems-la Mirada — Covina, Ca, CA 2022 annual report | 10.8 ng/L | 2.7× the limit |
| Hamden, CT 2024 annual report | 0–10.7 ng/L | 2.7× the limit |
| Maywood Mutual Water Co. #1 — Huntington Park, Ca, CA 2022 annual report | 10.6 ng/L | 2.6× the limit |
| Del Rio Mutual — El Monte, Ca, CA 2021 annual report | 10.5 ng/L | 2.6× the limit |
| Gilbert, AZ 2024 annual report | 9.8 ng/L | 2.5× the limit |
| Monrovia-city, Water Dept. — Monrovia, Ca, CA 2021 annual report | 9.78 ng/L | 2.4× the limit |
| Charleston, SC 2024 annual report | 9.7 ng/L | 2.4× the limit |
| Del Rio Mutual — El Monte, Ca, CA 2022 annual report | 9.7 ng/L | 2.4× the limit |
| North Charleston, SC 2024 annual report | 9.7 ng/L | 2.4× the limit |
| California Rehabilitation Center - Norco — Norco, Ca, CA 2022 annual report | 0–9.6 ng/L | 2.4× the limit |
| Dayton, OH 2024 annual report | 9.48 ng/L | 2.4× the limit |
| Augusta, GA 2024 annual report | 9.4 ng/L | 2.4× the limit |
| California Domestic Water Company — Whittier, Ca, CA 2020 annual report | 9.2 ng/L | 2.3× the limit |
| California Domestic Water Company — Whittier, Ca, CA 2021 annual report | 9.1 ng/L | 2.3× the limit |
| Maywood Mutual Water Co. #1 — Huntington Park, Ca, CA 2023 annual report | 9.1 ng/L | 2.3× the limit |
| High Point, NC 2024 annual report | 9 ng/L | 2.3× the limit |
| Tempe, AZ 2024 annual report | 9 ng/L | 2.3× the limit |
| Monrovia-city, Water Dept. — Monrovia, Ca, CA 2023 annual report | 8.95 ng/L | 2.2× the limit |
| Palm Bay, FL 2024 annual report | 7.3–8.7 ng/L | 2.2× the limit |
| Columbus, GA 2024 annual report | 5–8.4 ng/L | 2.1× the limit |
| Suburban Water Systems - Sativa — Covina, Ca, CA 2023 annual report | 8.4 ng/L | 2.1× the limit |
| San Bernardino Valley Wd — San Bernardino, Ca, CA 2023 annual report | 0–8.3 ng/L | 2.1× the limit |
| West Valley Water District — Rialto, Ca, CA 2023 annual report | 0–8.3 ng/L | 2.1× the limit |
| Brownsville, TX 2024 annual report | 8.2 ng/L | 2.0× the limit |
| Santa Fe Springs - City, Water Dept. — Santa Fe Springs, Ca, CA 2022 annual report | 8.1 ng/L | 2.0× the limit |
| Suburban Water Systems-la Mirada — Covina, Ca, CA 2023 annual report | 8.1 ng/L | 2.0× the limit |
| Toledo, OH 2024 annual report | 0–7.6 ng/L | 1.9× the limit |
| Gswc - Artesia — Anaheim, Ca, CA 2022 annual report | 7.4 ng/L | 1.9× the limit |
| Valley of Enchantment Mwc — Crestline, Ca, CA 2023 annual report | 0–7.1 ng/L | 1.8× the limit |
| Fort Worth, TX 2024 annual report | 7 ng/L | 1.8× the limit |
| Goodyear, AZ 2024 annual report | 7 ng/L | 1.8× the limit |
| Columbia, SC 2024 annual report | 6.8999999999999995 ng/L | 1.7× the limit |
| Allentown, PA 2024 annual report | 0–6.87 ng/L | 1.7× the limit |
| Jersey City, NJ 2024 annual report | 6.8 ng/L | 1.7× the limit |
| Monrovia-city, Water Dept. — Monrovia, Ca, CA 2022 annual report | 6.5 ng/L | 1.6× the limit |
| Paradise Ranch Mhp — Beverly Hills, Ca, CA 2023 annual report | 6.5 ng/L | 1.6× the limit |
| Santa Clarita, CA 2024 annual report | 6.5 ng/L | 1.6× the limit |
| Fullerton, CA 2024 annual report | 6.4 ng/L | 1.6× the limit |
| City of Orange — Orange, Ca, CA 2022 annual report | 6.1 ng/L | 1.5× the limit |
| Lake Arrowhead Csd — Lake Arrowhead, Ca, CA 2023 annual report | 6.1 ng/L | 1.5× the limit |
| Montara Water and Sanitary District — Montara, Ca, CA 2023 annual report | 0–6 ng/L | 1.5× the limit |
| Monrovia-city, Water Dept. — Monrovia, Ca, CA 2020 annual report | 5.85 ng/L | 1.5× the limit |
| Huntington Park-city, Water Dept. — Huntington Park, Ca, CA 2023 annual report | 5.83 ng/L | 1.5× the limit |
| Boca Raton, FL 2024 annual report | 5.8 ng/L | 1.4× the limit |
| Burbank, CA 2024 annual report | 0–5.8 ng/L | 1.4× the limit |
| Desert Water Agency — Palm Springs, Ca, CA 2023 annual report | 5.5 ng/L | 1.4× the limit |
| Gswc-south Arcadia — San Dimas, Ca, CA 2023 annual report | 5.4 ng/L | 1.4× the limit |
| Edison, NJ 2024 annual report | 5 ng/L | 1.3× the limit |
| Elizabeth, NJ 2024 annual report | 5 ng/L | 1.3× the limit |
| Gswc - Artesia — Anaheim, Ca, CA 2023 annual report | 5 ng/L | 1.3× the limit |
| Huntington Beach, CA 2025 annual report | 5 ng/L | 1.3× the limit |
| City of Garden Grove — Garden Grove, Ca, CA 2023 annual report | 4.7 ng/L | 1.2× the limit |
| Raleigh, NC 2024 annual report | 4.57 ng/L | 1.1× the limit |
| Town of Garner, NC 2024 annual report | 4.57 ng/L | 1.1× the limit |
| Town of Knightdale, NC 2024 annual report | 4.57 ng/L | 1.1× the limit |
| Town of Rolesville, NC 2024 annual report | 4.57 ng/L | 1.1× the limit |
| Town of Wake Forest, NC 2024 annual report | 4.57 ng/L | 1.1× the limit |
| Town of Wendell, NC 2024 annual report | 4.57 ng/L | 1.1× the limit |
| Town of Zebulon, NC 2024 annual report | 4.57 ng/L | 1.1× the limit |
| Los Angeles Cwwd 36-val Verde — Alhambra, Ca, CA 2023 annual report | 4.5 ng/L | 1.1× the limit |
| New Orleans, LA 2024 annual report | 0–4.5 ng/L | 1.1× the limit |
| San Miguel Community Services District — San Miguel, Ca, CA 2023 annual report | 0–4.5 ng/L | 1.1× the limit |
| Elsinore Valley MWD — Lake Elsinore, Ca, CA 2022 annual report | 0–4.3 ng/L | 1.1× the limit |
| Monterey Park-city, Water Dept. — Monterey Park, Ca, CA 2023 annual report | 0–4.3 ng/L | 1.1× the limit |
| City of Brea — Brea, Ca, CA 2021 annual report | 4.2 ng/L | 1.1× the limit |
| Lynn, MA 2024 annual report | 4.2 ng/L | 1.1× the limit |
| Backbone Mountain Boys Camp, MD 2024 annual report | 4 ng/L | 1.0× the limit |
| Campus Hills, MD 2024 annual report | 4 ng/L | 1.0× the limit |
| Cheltenham Youth Facility, MD 2024 annual report | 4 ng/L | 1.0× the limit |
| City of Lincoln — Lincoln, Ca, CA 2023 annual report | 4 ng/L | 1.0× the limit |
| Crescenta Valley Cwd — La Crescenta, Ca, CA 2022 annual report | 0.78–4 ng/L | 1.0× the limit |
| Eastern Correctional Institute, MD 2024 annual report | 4 ng/L | 1.0× the limit |
| Town of Accident, MD 2024 annual report | 4 ng/L | 1.0× the limit |
| Valencia Heights Water Co. — West Covina, Ca, CA 2022 annual report | 4 ng/L | 1.0× the limit |
Approaching the limit (7)
| Water system | Measured | vs. limit |
|---|---|---|
| Newark, NJ 2024 annual report | 3.8 ng/L | 0.9× the limit |
| Santa Ana, CA 2024 annual report | 3.8 ng/L | 0.9× the limit |
| Cal Am - Meadowbrook — Sacramento, Ca, CA 2023 annual report | 3.6 ng/L | 0.9× the limit |
| Philadelphia, PA 2023 annual report | 3.6 ng/L | 0.9× the limit |
| Big Bear City Csd — Big Bear City, Ca, CA 2023 annual report | 3.52 ng/L | 0.9× the limit |
| Rowland Water District — Rowland Heights, Ca, CA 2023 annual report | 0–3.4 ng/L | 0.8× the limit |
| Mendota, City of — Mendota, Ca, CA 2023 annual report | 3.3 ng/L | 0.8× the limit |
Within the federal limit (172)
| Water system | Measured |
|---|---|
| Broken Arrow, OK 2024 annual report | 3.025 ng/L |
| Centennial, CO 2023 annual report | 3.02 ng/L |
| Estero Municipal Improvement District — Foster City, Ca, CA 2023 annual report | 3 ng/L |
| Bradford Estates, MD 2024 annual report | 2.9 ng/L |
| Slo Csa No. 16 - Shandon — San Luis Obispo, Ca, CA 2023 annual report | 2.7 ng/L |
| Poolesville, MD 2024 annual report | 2.653 ng/L |
| Cal American Wc - Rio Plaza — Rosemead, Ca, CA 2023 annual report | 2.5 ng/L |
| Naval Base Ventura County, Point Mugu — Point Mugu, Ca, CA 2023 annual report | 1.8–2.5 ng/L |
| Naval Base Ventura County, Port Hueneme — Point Mugu, Ca, CA 2023 annual report | 1.8–2.5 ng/L |
| Port Hueneme City Water Dept — Port Hueneme, Ca, CA 2023 annual report | 1.8–2.5 ng/L |
| Thornton, CO 2024 annual report | 0–2.5 ng/L |
| City of Baltimore, MD 2024 annual report | 2.43 ng/L |
| Camp Pendleton (north) — Camp Pendleton, Ca, CA 2023 annual report | 0–2.4 ng/L |
| Camp Pendleton (south) — Camp Pendleton, Ca, CA 2023 annual report | 0–2.4 ng/L |
| Grand Rapids, MI 2025 annual report | 2.4 ng/L |
| Kent, WA 2024 annual report | 2.28 ng/L |
| Brown Deer, WI 2023 annual report | 2.2 ng/L |
| Butler, WI 2023 annual report | 2.2 ng/L |
| Franklin, WI 2023 annual report | 2.2 ng/L |
| Green Bay, WI 2024 annual report | 2.2 ng/L |
| Greendale, WI 2023 annual report | 2.2 ng/L |
| Greenfield, WI 2023 annual report | 2.2 ng/L |
| Hales Corners, WI 2023 annual report | 2.2 ng/L |
| Menomonee Falls, WI 2023 annual report | 2.2 ng/L |
| Mequon, WI 2023 annual report | 2.2 ng/L |
| Milwaukee, WI 2023 annual report | 2.2 ng/L |
| New Berlin, WI 2023 annual report | 2.2 ng/L |
| Rochester, NY 2024 annual report | 0–2.2 ng/L |
| Santa Cruz Water Department — Santa Cruz, Ca, CA 2023 annual report | 0–2.2 ng/L |
| Shorewood, WI 2023 annual report | 2.2 ng/L |
| St. Francis, WI 2023 annual report | 2.2 ng/L |
| Thiensville, WI 2023 annual report | 2.2 ng/L |
| Waukesha, WI 2023 annual report | 2.2 ng/L |
| Wauwatosa, WI 2023 annual report | 2.2 ng/L |
| West Allis, WI 2023 annual report | 2.2 ng/L |
| Santa Fe I.d. — Rancho Santa Fe, Ca, CA 2023 annual report | 0–2.1 ng/L |
| Washington Dc, DC 2023 annual report | 2.1 ng/L |
| Albany, NY 2024 annual report | 2 ng/L |
| Cal Am Water Company - Monterey — Pacific Grove, Ca, CA 2023 annual report | 2 ng/L |
| California State Prison - Solano — Vacaville, Ca, CA 2023 annual report | 2 ng/L |
| Lees Summit, MO 2025 annual report | 2 ng/L |
| Rockville, MD 2024 annual report | 2 ng/L |
| Vacaville, CA 2024 annual report | 2 ng/L |
| Yonkers, NY 2024 annual report | 1.9 ng/L |
| City of Fresno — Fresno, Ca, CA 2023 annual report | 1.82 ng/L |
| Rancho California Water District — Temecula, Ca, CA 2023 annual report | 1.8 ng/L |
| Saint Paul, MN 2024 annual report | 0–1.8 ng/L |
| San Jose Water — San Jose, Ca, CA 2021 annual report | 1.8 ng/L |
| Bend, OR 2025 annual report | 1.7 ng/L |
| Winston Salem, NC 2024 annual report | 1.68 ng/L |
Showing 50 of 172. The full list is in the JSON API.
Frequently asked
+What is PFOS?
Perfluorooctanesulfonic acid, a PFAS 'forever chemical' once used in firefighting foam and coatings. Linked to cancer, thyroid disease, and immune effects; the EPA set an enforceable limit of 4 parts per trillion.
+What is the federal limit for PFOS in drinking water?
The federal MCL for PFOS is 4 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 PFOS over the federal limit?
148 of the 327 public water systems on The Water Map report PFOS at or above its federal limit, spanning 31 U.S. states. The full list is on this page.
+How can I check if PFOS 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 PFOS.