Inorganic chemicals
Nitrate in U.S. tap water
1,169 public water systems across 40 U.S. states report Nitrate in their annual Consumer Confidence Report. 39 sit at or above the federal limit.
1169
systems measuring
39
over the limit
40
states represented
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.
Federal limit10 mg/L· MCL
At or above the federal limit (39)
| Water system | Measured | vs. limit |
|---|---|---|
| Pittsburgh, PA 2024 annual report | 101 mg/L | 10.1× the limit |
| Morro Bay Pw Dept - Water Division — Morro Bay, Ca, CA 2023 annual report | 14–73 mg/L | 7.3× the limit |
| San Miguelito Mwc — Avila Beach, Ca, CA 2023 annual report | 0–40 mg/L | 4.0× the limit |
| Hilmar County Water District — Hilmar, Ca, CA 2023 annual report | 1–34.3 mg/L | 3.4× the limit |
| Crescenta Valley Cwd — La Crescenta, Ca, CA 2021 annual report | 16.1–33.1 mg/L | 3.3× the limit |
| Crescenta Valley Cwd — La Crescenta, Ca, CA 2022 annual report | 13.3–32.8 mg/L | 3.3× the limit |
| La Verne, City Wd — La Verne, Ca, CA 2023 annual report | 4–26 mg/L | 2.6× the limit |
| La Verne, City Wd — La Verne, Ca, CA 2022 annual report | 4–26 mg/L | 2.6× the limit |
| La Verne, City Wd — La Verne, Ca, CA 2021 annual report | 4–26 mg/L | 2.6× the limit |
| La Verne, City Wd — La Verne, Ca, CA 2020 annual report | 0–25 mg/L | 2.5× the limit |
| Pine Valley Mutual Wc — Pine Valley, Ca, CA 2023 annual report | 24 mg/L | 2.4× the limit |
| Wasco, City of — Wasco, Ca, CA 2023 annual report | 0.45–21 mg/L | 2.1× the limit |
| Corona, City of — Corona, Ca, CA 2023 annual report | 0–20 mg/L | 2.0× the limit |
| San Bernardino City — San Bernardino, Ca, CA 2023 annual report | 17.6 mg/L | 1.8× the limit |
| Templeton Csd — Templeton, Ca, CA 2023 annual report | 0–17.1 mg/L | 1.7× the limit |
| Sleepy Valley Water Company — Santa Clarita, Ca, CA 2020 annual report | 14.7 mg/L | 1.5× the limit |
| Golden State Water Company - Simi Valley — Rancho Cordova, Ca, CA 2023 annual report | 13 mg/L | 1.3× the limit |
| Western Hills Water District/diablo Gran — Patterson, Ca, CA 2023 annual report | 0–13 mg/L | 1.3× the limit |
| Winton Water & Sanitary Dist — Winton, Ca, CA 2023 annual report | 12.28 mg/L | 1.2× the limit |
| City of Millbrae — Millbrae, Ca, CA 2021 annual report | 12 mg/L | 1.2× the limit |
| City of Live Oak — Live Oak, Ca, CA 2022 annual report | 11.2 mg/L | 1.1× 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 |
| Tipton Community Services Dist — Tipton, Ca, CA 2022 annual report | 11 mg/L | 1.1× the limit |
| Denair Community Services District — Denair, Ca, CA 2023 annual report | 3.18–10.3 mg/L | 1.0× the limit |
| Sleepy Valley Water Company — Santa Clarita, Ca, CA 2021 annual report | 10.2 mg/L | 1.0× the limit |
| Camp Williams-resort Water — Manhattan Beach, Ca, CA 2021 annual report | 10 mg/L | 1.0× the limit |
| Catoosa Utility District Authority, TN 2025 annual report | 10 mg/L | 1.0× the limit |
| Chattanooga, TN 2025 annual report | 10 mg/L | 1.0× the limit |
| City of Gustine — Gustine, Ca, CA 2022 annual report | 1.2–10 mg/L | 1.0× the limit |
| East Ridge, TN 2025 annual report | 10 mg/L | 1.0× the limit |
| Frisco, TX 2024 annual report | 10 mg/L | 1.0× the limit |
| Goodyear, AZ 2024 annual report | 10 mg/L | 1.0× the limit |
| Lookout Mountain, TN 2025 annual report | 10 mg/L | 1.0× the limit |
| Pixley Public Util Dist — Pixley, Ca, CA 2023 annual report | 10 mg/L | 1.0× the limit |
| Red Bank, TN 2025 annual report | 10 mg/L | 1.0× the limit |
| Rossville, TN 2025 annual report | 10 mg/L | 1.0× the limit |
| Signal Mountain, TN 2025 annual report | 10 mg/L | 1.0× the limit |
| Walker County, TN 2025 annual report | 10 mg/L | 1.0× the limit |
Approaching the limit (33)
| Water system | Measured | vs. limit |
|---|---|---|
| Keyes Community Services Dist. — Keyes, Ca, CA 2023 annual report | 0.79–9.99 mg/L | 1.0× the limit |
| The River Community — Azusa, Ca, CA 2022 annual report | 0–9.7 mg/L | 1.0× the limit |
| Shafter, City of — Shafter, Ca, CA 2022 annual report | 1.7–9.6 mg/L | 1.0× the limit |
| Los Osos Community Services District — Los Osos, Ca, CA 2023 annual report | 3.3–9.5 mg/L | 0.9× the limit |
| Delhi Cwd — Delhi, Ca, CA 2023 annual report | 1.18–9.34 mg/L | 0.9× the limit |
| Gaither Manor Apartments, MD 2024 annual report | 9.3 mg/L | 0.9× the limit |
| Pinedale County Water District — Pinedale, Ca, CA 2023 annual report | 0–9.2 mg/L | 0.9× the limit |
| Thunderbird Cwd — Apple Valley, Ca, CA 2023 annual report | 9.1 mg/L | 0.9× the limit |
| Bakman Water Company — Fresno, Ca, CA 2023 annual report | 2–9 mg/L | 0.9× the limit |
| Cedar Rapids, IA 2024 annual report | 0–9 mg/L | 0.9× the limit |
| City of Livingston — Livingston, Ca, CA 2023 annual report | 0.23–9 mg/L | 0.9× the limit |
| City of Robins, IA 2024 annual report | 0–9 mg/L | 0.9× the limit |
| Coachella Vwd: Cove Community — Palm Desert, Ca, CA 2023 annual report | 0–9 mg/L | 0.9× the limit |
| Coachella Vwd: I.d. No. 8 — Palm Desert, Ca, CA 2023 annual report | 0–9 mg/L | 0.9× the limit |
| Glenbrook Cove Subdivision of Marion, IA 2024 annual report | 0–9 mg/L | 0.9× the limit |
| Planada Csd — Planada, Ca, CA 2023 annual report | 2.9–9 mg/L | 0.9× the limit |
| Poweshiek Water Association, IA 2024 annual report | 0–9 mg/L | 0.9× the limit |
| Cal/am Water Company - Baldwin Hills — Rosemead, Ca, CA 2020 annual report | 8.7 mg/L | 0.9× the limit |
| Quartz Hill Water Dist. — Quartz Hill, Ca, CA 2022 annual report | 0.78–8.7 mg/L | 0.9× the limit |
| Tehachapi, City of — Tehachapi, Ca, CA 2022 annual report | 2.3–8.7 mg/L | 0.9× the limit |
| Quartz Hill Water Dist. — Quartz Hill, Ca, CA 2020 annual report | 0.89–8.6 mg/L | 0.9× the limit |
| Stallion Springs Csd — Tehachapi, Ca, CA 2023 annual report | 0–8.5 mg/L | 0.8× the limit |
| Bradford Estates, MD 2024 annual report | 8.4 mg/L | 0.8× the limit |
| Chino, City of — Chino, Ca, CA 2023 annual report | 1.2–8.4 mg/L | 0.8× the limit |
| Quartz Hill Water Dist. — Quartz Hill, Ca, CA 2023 annual report | 0.79–8.4 mg/L | 0.8× the limit |
| Avondale, AZ 2024 annual report | 0–8.2 mg/L | 0.8× the limit |
| Quartz Hill Water Dist. — Quartz Hill, Ca, CA 2021 annual report | 0.9–8.2 mg/L | 0.8× the limit |
| Boh Nak Mhp, MD 2024 annual report | 8.1 mg/L | 0.8× the limit |
| City of Arcadia — Arcadia, Ca, CA 2022 annual report | 0.47–8.1 mg/L | 0.8× the limit |
| Pico Wd — Pico Rivera, Ca, CA 2020 annual report | 8.1 mg/L | 0.8× the limit |
| Poolesville, MD 2024 annual report | 8.05 mg/L | 0.8× the limit |
| Lake Elizabeth Mutual Water Co. — Elizabeth Lake, Ca, CA 2023 annual report | 4.2–8 mg/L | 0.8× the limit |
| Palo Alto Park Mutual Water Company — East Palo Alto, Ca, CA 2023 annual report | 8 mg/L | 0.8× the limit |
Within the federal limit (1097)
Showing 50 of 1097. 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?
39 of the 1169 public water systems on The Water Map report Nitrate at or above its federal limit, spanning 40 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.