Inorganic chemicals
Nitrate in U.S. tap water
318 public water systems across 41 U.S. states report Nitrate in their annual Consumer Confidence Report. 15 sit at or above the federal limit.
What it is
A compound from fertilizer runoff, septic systems, and erosion of natural deposits.
Why it's regulated
Levels above the federal limit can cause 'blue baby syndrome,' a serious oxygen-transport condition in infants.
At or above the federal limit (15)
| Water system | Measured | vs. limit |
|---|---|---|
| Columbus, OH 2025 annual report | 2025 mg/L | 202.5× the limit |
| Hollywood, FL 2024 annual report | 2024 mg/L | 202.4× the limit |
| Mcallen, TX 2024 annual report | 2024 mg/L | 202.4× the limit |
| Lakewood, CO 2024 annual report | 119 ug/L | 11.9× the limit |
| Pittsburgh, PA 2024 annual report | 101 mg/L | 10.1× the limit |
| Centennial, CO 2023 annual report | 91 ug/L | 9.1× the limit |
| Denver, CO 2023 annual report | 91 ug/L | 9.1× the limit |
| Albuquerque, NM 2024 annual report | 0.38 | 7.6× the limit |
| City of Hialeah, FL 2023 annual report | 15 mg/L | 1.5× the limit |
| City of Homestead, FL 2023 annual report | 15 mg/L | 1.5× the limit |
| City of North Miami Beach, FL 2023 annual report | 15 mg/L | 1.5× the limit |
| Miami Dade, FL 2023 annual report | 15 mg/L | 1.5× the limit |
| Arlington, TX 2024 annual report | 11 mg/L | 1.1× the limit |
| Glendale, CA 2024 annual report | 11 mg/L | 1.1× the limit |
| Goodyear, AZ 2024 annual report | 10 mg/L | 1.0× the limit |
Approaching the limit (7)
| Water system | Measured | vs. limit |
|---|---|---|
| Gaither Manor Apartments, MD 2024 annual report | 8.1–9.3 mg/L | 0.9× the limit |
| Cedar Rapids, IA 2024 annual report | 0–9 mg/L | 0.9× the limit |
| City of Robins, IA 2024 annual report | 0–9 mg/L | 0.9× the limit |
| Glenbrook Cove Subdivision of Marion, IA 2024 annual report | 9 mg/L | 0.9× the limit |
| Poweshiek Water Association, IA 2024 annual report | 9 mg/L | 0.9× the limit |
| Bradford Estates, MD 2024 annual report | 5.3–8.4 | 0.8× the limit |
| Avondale, AZ 2024 annual report | 0–8.2 mg/L | 0.8× the limit |
Within the federal limit (292)
| Water system | Measured |
|---|---|
| Mesa, AZ 2024 annual report | 7.88 mg/L |
| Tucson, AZ 2024 annual report | 0–7.2 mg/L |
| El Monte, CA 2024 annual report | 2.4–7.1 mg/L |
| San Francisco SFPUC, CA 2023 annual report | 7.1 mg/L |
| Amelano Manor, MD 2024 annual report | 7 mg/L |
| Pomona, CA 2024 annual report | 0–7 mg/L |
| Tempe, AZ 2024 annual report | 0–7 mg/L |
| Ontario, CA 2024 annual report | 6.7 mg/L |
| Chapel Hill Water System, MD 2024 annual report | 6.46 mg/L |
| Chandler, AZ 2024 annual report | 6.2 mg/L |
| Burbank, CA 2024 annual report | 0–5.8 mg/L |
| Bennett Mhp, MD 2024 annual report | 5.4 mg/L |
| Riverside, CA 2024 annual report | 5.4 |
| Carpenters Point, MD 2024 annual report | 5.31 mg/L |
| Betterton, MD 2024 annual report | 5 mg/L |
| Buckeye, AZ 2024 annual report | 5 mg/L |
| Granite Mhp, MD 2024 annual report | 5 mg/L |
| Allentown, PA 2024 annual report | 2.84–4.96 mg/L |
| Town of Berlin, MD 2024 annual report | 5–4.8 mg/L |
| Campus Hills, MD 2024 annual report | 4.7–4.7 mg/L |
| Vancouver, WA 2024 annual report | 4.7 mg/L |
| Ansonia, CT 2024 annual report | 0–4.61 |
| Bethany, CT 2024 annual report | 0–4.61 |
| Branford, CT 2024 annual report | 0–4.61 |
| Cheshire, CT 2024 annual report | 0–4.61 |
| Derby, CT 2024 annual report | 0–4.61 |
| East Haven, CT 2024 annual report | 0–4.61 |
| Hamden, CT 2024 annual report | 0–4.61 |
| Milford, CT 2024 annual report | 0–4.61 |
| New Haven, CT 2024 annual report | 0–4.61 |
| North Haven, CT 2024 annual report | 0–4.61 |
| Orange, CT 2024 annual report | 0–4.61 |
| Seymour, CT 2024 annual report | 0–4.61 |
| West Haven, CT 2024 annual report | 0–4.61 |
| Woodbridge, CT 2024 annual report | 0–4.61 |
| Pasadena, CA 2023 annual report | 4.6 mg/L |
| Philadelphia, PA 2023 annual report | 4.52 |
| Boonsboro Keedysville, MD 2024 annual report | 4.5 mg/L |
| Gilbert, AZ 2024 annual report | 4.27 mg/L |
| Tacoma, WA 2024 annual report | 4.26 |
| Clovis, CA 2024 annual report | 4.23 mg/L |
| Salt Lake City, UT 2024 annual report | 0.16–4.18 |
| Cedar Ridge, MD 2024 annual report | 4 mg/L |
| Meridian, ID 2024 annual report | 4 mg/L |
| St George, UT 2024 annual report | 4 mg/L |
| Phoenix, AZ 2025 annual report | 3.8 mg/L |
| Rialto, CA 2024 annual report | 3.8 mg/L |
| Benedictine School, MD 2024 annual report | 3.74 mg/L |
| Rancho Cucamonga, CA 2024 annual report | 3.68 mg/L |
| Huntsville, AL 2024 annual report | 0.57–3.5 mg/L |
Showing 50 of 292. The full list is in the JSON API.
Frequently asked
+What is Nitrate?
A compound from fertilizer runoff, septic systems, and erosion of natural deposits. Levels above the federal limit can cause 'blue baby syndrome,' a serious oxygen-transport condition in infants.
+What is the federal limit for Nitrate in drinking water?
The federal MCL for Nitrate is 10 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 Nitrate over the federal limit?
15 of the 318 public water systems on The Water Map report Nitrate at or above its federal limit, spanning 41 U.S. states. The full list is on this page.
+How can I check if Nitrate 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 Nitrate.