Disinfectants
Chlorine in U.S. tap water
705 public water systems across 36 U.S. states report Chlorine in their annual Consumer Confidence Report. 21 sit at or above the federal limit.
705
systems measuring
21
over the limit
36
states represented
What it is
A disinfectant added to drinking water to kill bacteria and viruses.
Why it's regulated
Effective and necessary, but high residual levels can cause taste and odor issues; the EPA caps the residual disinfectant level.
Federal limit4 mg/L· MCL
At or above the federal limit (21)
| Water system | Measured | vs. limit |
|---|---|---|
| Pittsburgh, PA 2024 annual report | 104 mg/L | 26.0× the limit |
| Amelano Manor, MD 2024 annual report | 1.4–11 mg/L | 2.8× the limit |
| Santa Fe I.d. — Rancho Santa Fe, Ca, CA 2023 annual report | 0–10 mg/L | 2.5× the limit |
| Glendora-city, Water Dept. — Glendora, Ca, CA 2021 annual report | 0.03–6.4 mg/L | 1.6× the limit |
| Chapel Hill Water System, MD 2024 annual report | 3.54–6 mg/L | 1.5× the limit |
| City of Hampton, VA 2024 annual report | 0–5.4 mg/L | 1.4× the limit |
| City of Newport News, VA 2025 annual report | 0–5.4 mg/L | 1.4× the limit |
| City of Poquoson, VA 2024 annual report | 0–5.4 mg/L | 1.4× the limit |
| City of Poquoson, VA 2025 annual report | 0–5.4 mg/L | 1.4× the limit |
| Hampton, VA 2025 annual report | 0–5.4 mg/L | 1.4× the limit |
| James City County, VA 2025 annual report | 0–5.4 mg/L | 1.4× the limit |
| Newport News, VA 2024 annual report | 0–5.4 mg/L | 1.4× the limit |
| York County, VA 2024 annual report | 0–5.4 mg/L | 1.4× the limit |
| Palm Coast, FL 2024 annual report | 0.6–5.1 mg/L | 1.3× the limit |
| Cedarhurst Mhp, MD 2024 annual report | 4 mg/L | 1.0× the limit |
| City of Lighthouse Point, FL 2024 annual report | 0.62–4 mg/L | 1.0× the limit |
| Eden Mobile Home Park, MD 2024 annual report | 4 mg/L | 1.0× the limit |
| Esparto C.s.d. — Esparto, Ca, CA 2023 annual report | 0–4 mg/L | 1.0× the limit |
| Frisco, TX 2024 annual report | 4 mg/L | 1.0× the limit |
| Pompano Beach, FL 2024 annual report | 0.62–4 mg/L | 1.0× the limit |
| Town of Lauderdale-by-the-sea, FL 2024 annual report | 0.62–4 mg/L | 1.0× the limit |
Approaching the limit (19)
| Water system | Measured | vs. limit |
|---|---|---|
| Thornton, CO 2024 annual report | 1.7–3.9 mg/L | 1.0× the limit |
| Morro Bay Pw Dept - Water Division — Morro Bay, Ca, CA 2023 annual report | 0.18–3.84 mg/L | 1.0× the limit |
| Cal-am Water Coronado — Imperial Beach, Ca, CA 2023 annual report | 3.8 mg/L | 0.9× the limit |
| Coral Springs, FL 2024 annual report | 0.8–3.8 mg/L | 0.9× the limit |
| Hialeah, FL 2023 annual report | 3.8 mg/L | 0.9× the limit |
| Huntsville, AL 2024 annual report | 2.1–3.8 mg/L | 0.9× the limit |
| Valencia Heights Water Co. — West Covina, Ca, CA 2022 annual report | 0.3–3.8 mg/L | 0.9× the limit |
| Valencia Heights Water Co. — West Covina, Ca, CA 2020 annual report | 0.04–3.8 mg/L | 0.9× the limit |
| Columbus, GA 2024 annual report | 1.6–3.76 mg/L | 0.9× the limit |
| West Palm Beach, FL 2024 annual report | 0–3.7 mg/L | 0.9× the limit |
| Fort Myers, FL 2024 annual report | 0–3.68 mg/L | 0.9× the limit |
| City of Alhambra — Alhambra, Ca, CA 2023 annual report | 0.01–3.59 mg/L | 0.9× the limit |
| Wichita Falls, TX 2024 annual report | 3–3.56 mg/L | 0.9× the limit |
| Jacksonville, FL 2024 annual report | 0.21–3.5 mg/L | 0.9× the limit |
| Santa Monica-city, Water Division — Los Angeles, Ca, CA 2023 annual report | 0–3.5 mg/L | 0.9× the limit |
| Cary, NC 2025 annual report | 0.37–3.29 mg/L | 0.8× the limit |
| Woodlands Development — Arroyo Grande, Ca, CA 2023 annual report | 0.05–3.29 mg/L | 0.8× the limit |
| Santa Ynez River Water Cons. Dist. Id#1 — Santa Ynez, Ca, CA 2023 annual report | 0.3–3.22 mg/L | 0.8× the limit |
| Solvang Water Division — Solvang, Ca, CA 2023 annual report | 0.3–3.22 mg/L | 0.8× the limit |
Within the federal limit (664)
| Water system | Measured |
|---|---|
| Saint Paul, MN 2024 annual report | 2.56–3.11 mg/L |
| Cambridge, MA 2024 annual report | 0.78–3.05 mg/L |
| City of San Bruno — San Bruno, Ca, CA 2023 annual report | 3.03 mg/L |
| Cape Coral, FL 2024 annual report | 0.21–3 mg/L |
| City of Millbrae — Millbrae, Ca, CA 2021 annual report | 3 mg/L |
| Coachella Vwd: Cove Community — Palm Desert, Ca, CA 2023 annual report | 0–3 mg/L |
| Coachella Vwd: I.d. No. 8 — Palm Desert, Ca, CA 2023 annual report | 0–3 mg/L |
| Des Moines, IA 2024 annual report | 1.7–3 mg/L |
| Town of Denton, MD 2024 annual report | 3 mg/L |
| Delano, City of — Delano, Ca, CA 2023 annual report | 1.33–2.98 mg/L |
| Birmingham, AL 2024 annual report | 1.4–2.97 mg/L |
| Boca Raton, FL 2024 annual report | 2.9 mg/L |
| Hayward, CA 2024 annual report | 2.9 mg/L |
| Lexington, KY 2024 annual report | 2.9 mg/L |
| Nacimiento Water Company — Bradley, Ca, CA 2023 annual report | 0.9–2.9 mg/L |
| Daly City, CA 2024 annual report | 2.82 mg/L |
| City of Palo Alto — Palo Alto, Ca, CA 2023 annual report | 2.81 mg/L |
| City of Brisbane — Brisbane, Ca, CA 2023 annual report | 2.8 mg/L |
| City of Cumberland, MD 2024 annual report | 2.1–2.8 mg/L |
| Eastern Region Allegany Distrib System, MD 2024 annual report | 2.1–2.8 mg/L |
| Guadalupe Valley Mid — Brisbane, Ca, CA 2023 annual report | 2.8 mg/L |
| Lake Hemet MWD — Hemet, Ca, CA 2023 annual report | 0.5–2.8 mg/L |
| Rio Cosumnes Correctional Center [sws] — Sacramento, Ca, CA 2023 annual report | 0.4–2.8 mg/L |
| City of Redwood City — Redwood City, Ca, CA 2023 annual report | 2.76 mg/L |
| City of Burlingame — Burlingame, Ca, CA 2023 annual report | 2.75 mg/L |
| Louisville, KY 2024 annual report | 2.71 mg/L |
| Desert Water Agency — Palm Springs, Ca, CA 2023 annual report | 0.33–2.7 mg/L |
| Glendora-city, Water Dept. — Glendora, Ca, CA 2022 annual report | 0.05–2.7 mg/L |
| Hamden, CT 2024 annual report | 0–2.7 mg/L |
| Tehachapi, City of — Tehachapi, Ca, CA 2022 annual report | 0.43–2.7 mg/L |
| Mid-peninsula Water District — Belmont, Ca, CA 2023 annual report | 2.68 mg/L |
| Laredo, TX 2024 annual report | 2.67 mg/L |
| Estero Municipal Improvement District — Foster City, Ca, CA 2023 annual report | 2.65 mg/L |
| Torrance, CA 2024 annual report | 0.13–2.64 mg/L |
| Richardson, TX 2024 annual report | 2.63 mg/L |
| City of Hialeah, FL 2023 annual report | 0.3–2.6 mg/L |
| City of North Miami Beach, FL 2023 annual report | 0.3–2.6 mg/L |
| Miami Dade, FL 2023 annual report | 0.4–2.6 mg/L |
| Los Osos Community Services District — Los Osos, Ca, CA 2023 annual report | 0.2–2.58 mg/L |
| Raleigh, NC 2024 annual report | 2.55 mg/L |
| Town of Garner, NC 2024 annual report | 2.55 mg/L |
| Town of Knightdale, NC 2024 annual report | 2.55 mg/L |
| Town of Rolesville, NC 2024 annual report | 2.55 mg/L |
| Town of Wake Forest, NC 2024 annual report | 2.55 mg/L |
| Town of Wendell, NC 2024 annual report | 2.55 mg/L |
| Town of Zebulon, NC 2024 annual report | 2.55 mg/L |
| Plano, TX 2024 annual report | 2.53 mg/L |
| San Bernardino Valley Wd — San Bernardino, Ca, CA 2023 annual report | 1.08–2.51 mg/L |
| West Valley Water District — Rialto, Ca, CA 2023 annual report | 1.08–2.51 mg/L |
| Calif State Polytechnical Univ - Pomona — Pomona, Ca, CA 2023 annual report | 2.5 mg/L |
Showing 50 of 664. The full list is in the JSON API.
Frequently asked
+What is Chlorine?
A disinfectant added to drinking water to kill bacteria and viruses. Effective and necessary, but high residual levels can cause taste and odor issues; the EPA caps the residual disinfectant level.
+What is the federal limit for Chlorine in drinking water?
The federal MCL for Chlorine is 4 mg/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 Chlorine over the federal limit?
21 of the 705 public water systems on The Water Map report Chlorine at or above its federal limit, spanning 36 U.S. states. The full list is on this page.
+How can I check if Chlorine 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 Chlorine.