Disinfectants
Chlorine in U.S. tap water
298 public water systems across 38 U.S. states report Chlorine in their annual Consumer Confidence Report. 30 sit at or above the federal limit.
298
systems measuring
30
over the limit
38
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· MRDL
At or above the federal limit (30)
| Water system | Measured | vs. limit |
|---|---|---|
| Pittsburgh, PA 2024 annual report | 104 mg/L | 520.0× the limit |
| Columbus, OH 2025 annual report | 2025 mg/L | 506.3× the limit |
| Albuquerque, NM 2024 annual report | 0.9 | 9.0× the limit |
| Chapel Hill Water System, MD 2024 annual report | 3.54–6 mg/L | 1.5× the limit |
| Tampa, FL 2024 annual report | 0.2–5.6 mg/L | 1.4× 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 | 1.4× the limit |
| City of Poquoson, VA 2025 annual report | 0–5.4 mg/L | 1.4× the limit |
| City of Poquoson, VA 2024 annual report | 0–5.4 | 1.4× the limit |
| Hampton, VA 2025 annual report | 0–5.4 | 1.4× the limit |
| James City County, VA 2025 annual report | 0–5.4 | 1.4× the limit |
| James City County, VA 2024 annual report | 0–5.4 | 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 | 1.4× the limit |
| York County, VA 2025 annual report | 0–5.4 | 1.4× the limit |
| Palm Coast, FL 2024 annual report | 0.6–5.1 mg/L | 1.3× the limit |
| Chesapeake, VA 2023 annual report | 3.3–4.6 mg/L | 1.1× the limit |
| City of Hemet, CA 2024 annual report | 0–4.3 mg/L | 1.1× the limit |
| City of Menifee, CA 2024 annual report | 0–4.3 mg/L | 1.1× the limit |
| City of Murrieta, CA 2024 annual report | 0–4.3 mg/L | 1.1× the limit |
| City of Perris, CA 2024 annual report | 0–4.3 mg/L | 1.1× the limit |
| City of San Jacinto, CA 2024 annual report | 0–4.3 mg/L | 1.1× the limit |
| City of Temecula, CA 2024 annual report | 0–4.3 mg/L | 1.1× the limit |
| East Valley Service Area, CA 2024 annual report | 0–4.3 mg/L | 1.1× the limit |
| Mills Service Area, CA 2024 annual report | 0–4.3 mg/L | 1.1× the limit |
| Moreno Valley, CA 2024 annual report | 0–4.3 mg/L | 1.1× the limit |
| Skinner Service Area, CA 2024 annual report | 0–4.3 mg/L | 1.1× the limit |
| West Palm Beach, FL 2024 annual report | 0.4–4.3 mg/L | 1.1× the limit |
| Cedarhurst Mhp, MD 2024 annual report | 4 mg/L | 1.0× the limit |
| Eden Mobile Home Park, MD 2024 annual report | 4 mg/L | 1.0× the limit |
Approaching the limit (11)
| Water system | Measured | vs. limit |
|---|---|---|
| Cedar Rapids, IA 2024 annual report | 1.9–3.8 mg/L | 0.9× the limit |
| City of Robins, IA 2024 annual report | 1.9–3.8 mg/L | 0.9× the limit |
| Coral Springs, FL 2024 annual report | 0.8–3.8 mg/L | 0.9× the limit |
| Glenbrook Cove Subdivision of Marion, IA 2024 annual report | 1.9–3.8 mg/L | 0.9× the limit |
| Huntsville, AL 2024 annual report | 2.1–3.8 mg/L | 0.9× the limit |
| Poweshiek Water Association, IA 2024 annual report | 1.9–3.8 mg/L | 0.9× the limit |
| Sioux Falls, SD 2024 annual report | 2.3–3.8 mg/L | 0.9× the limit |
| Columbus, GA 2024 annual report | 1.6–3.76 | 0.9× the limit |
| Wichita Falls, TX 2024 annual report | 3–3.56 | 0.9× the limit |
| Jacksonville, FL 2024 annual report | 0.21–3.5 mg/L | 0.9× the limit |
| Cary, NC 2025 annual report | 0.37–3.29 mg/L | 0.8× the limit |
Within the federal limit (232)
| Water system | Measured |
|---|---|
| Saint Paul, MN 2024 annual report | 2.56–3.11 mg/L |
| Cape Coral, FL 2024 annual report | 0.21–3 mg/L |
| Town of Denton, MD 2024 annual report | 3 mg/L |
| Washington Dc, DC 2023 annual report | 3 mg/L |
| Birmingham, AL 2024 annual report | 1.4–2.97 |
| Dallas, TX 2024 annual report | 2.97 mg/L |
| Boca Raton, FL 2024 annual report | 2.9 mg/L |
| Hayward, CA 2024 annual report | 2.9 mg/L |
| Thornton, CO 2024 annual report | 1.7–2.9 mg/L |
| Daly City, CA 2024 annual report | 2.82 mg/L |
| Lubbock, TX 2024 annual report | 2.78 mg/L |
| Louisville, KY 2024 annual report | 2.71 mg/L |
| Ansonia, CT 2024 annual report | 1.4–2.7 |
| Bethany, CT 2024 annual report | 1.4–2.7 |
| Branford, CT 2024 annual report | 1.4–2.7 |
| Cheshire, CT 2024 annual report | 1.4–2.7 |
| Derby, CT 2024 annual report | 1.4–2.7 |
| East Haven, CT 2024 annual report | 1.4–2.7 |
| Hamden, CT 2024 annual report | 1.4–2.7 |
| Milford, CT 2024 annual report | 1.4–2.7 |
| New Haven, CT 2024 annual report | 1.4–2.7 |
| North Haven, CT 2024 annual report | 1.4–2.7 |
| Orange, CT 2024 annual report | 1.4–2.7 |
| Seymour, CT 2024 annual report | 1.4–2.7 |
| West Haven, CT 2024 annual report | 1.4–2.7 |
| Woodbridge, CT 2024 annual report | 1.4–2.7 |
| Laredo, TX 2024 annual report | 2.67 mg/L |
| New Braunfels, TX 2024 annual report | 2.64 mg/L |
| Richardson, TX 2024 annual report | 2.63 mg/L |
| City of Hialeah, FL 2023 annual report | 1–2.6 mg/L |
| City of Homestead, FL 2023 annual report | 1–2.6 mg/L |
| City of North Miami Beach, FL 2023 annual report | 1.6–2.6 mg/L |
| Miami Dade, FL 2023 annual report | 1–2.6 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 |
| Irvine, CA 2023 annual report | 2.5 mg/L |
| Knoxville, TN 2024 annual report | 1.7–2.5 |
| Cambridge, MA 2024 annual report | 2.39 mg/L |
| Lakeland, FL 2024 annual report | 1.91–2.37 mg/L |
| Miramar, FL 2024 annual report | 1.93–2.26 mg/L |
| Mckinney, TX 2024 annual report | 2.24 mg/L |
| Wilmington, NC 2024 annual report | 0.35–2.2 mg/L |
| Kent, WA 2024 annual report | 2.18 |
| Costa Mesa, CA 2024 annual report | 2.11 mg/L |
Showing 50 of 232. 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 MRDL 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?
30 of the 298 public water systems on The Water Map report Chlorine at or above its federal limit, spanning 38 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.