We analyzed tap water quality data for hundreds of cities across the United States to identify those with the highest levels of nitrate. This ranking is based on 2026 data from the EPA and EWG databases.
Nitrate is a contaminant of growing concern in drinking water. The cities below have the highest detected levels based on the most recent testing data available.
Rankings at a Glance
Eola, Texas
Eola has nitrate detected at 33.60 ppm. 12 total contaminants were found in the water supply.
Aguanga, California
Aguanga has nitrate detected at 25 ppm. 8 total contaminants were found in the water supply.
Whitharral, Texas
Whitharral has nitrate detected at 24.40 ppm. 13 total contaminants were found in the water supply.
Edison, California
Edison has nitrate detected at 23 ppm. 14 total contaminants were found in the water supply.
Lemon Cove, California
Lemon Cove has nitrate detected at 19.40 ppm. 10 total contaminants were found in the water supply.
Morro Bay, California
Morro Bay has nitrate detected at 16.90 ppm. 26 total contaminants were found in the water supply.
Turkey, Texas
Turkey has nitrate detected at 16.90 ppm. 13 total contaminants were found in the water supply.
Ford, Kansas
Ford has nitrate detected at 16.70 ppm. 12 total contaminants were found in the water supply.
Grantville, Kansas
Grantville has nitrate detected at 16 ppm. 18 total contaminants were found in the water supply.
Bent, Texas
Bent has nitrate detected at 16 ppm. 14 total contaminants were found in the water supply.
Okarche, Oklahoma
Okarche has nitrate detected at 13.30 ppm. 10 total contaminants were found in the water supply.
Quitaque, Texas
Quitaque has nitrate detected at 13.30 ppm. 12 total contaminants were found in the water supply.
Turner, Montana
Turner has nitrate detected at 13.10 ppm. 6 total contaminants were found in the water supply.
Iuka, Kansas
Iuka has nitrate detected at 12.50 ppm. 14 total contaminants were found in the water supply.
Little Diomede, Alaska
Little Diomede has nitrate detected at 12.50 ppm. 11 total contaminants were found in the water supply.
Orwell, New York
Orwell has nitrate detected at 12.40 ppm. 12 total contaminants were found in the water supply.
Welch, Texas
Welch has nitrate detected at 12.20 ppm. 12 total contaminants were found in the water supply.
Corcoran, California
Corcoran has nitrate detected at 12 ppm. 26 total contaminants were found in the water supply.
Lewistown, Montana
Lewistown has nitrate detected at 11.90 ppm. 5 total contaminants were found in the water supply.
Montezuma, Indiana
Montezuma has nitrate detected at 11.70 ppm. 5 total contaminants were found in the water supply.
Barker, Texas
Barker has nitrate detected at 11.70 ppm. 4 total contaminants were found in the water supply.
Sylvia, Kansas
Sylvia has nitrate detected at 11.60 ppm. 14 total contaminants were found in the water supply.
Lenorah, Texas
Lenorah has nitrate detected at 11.40 ppm. 16 total contaminants were found in the water supply.
Valley Ford, California
Valley Ford has nitrate detected at 11.40 ppm. 14 total contaminants were found in the water supply.
Geary, Oklahoma
Geary has nitrate detected at 11.40 ppm. 11 total contaminants were found in the water supply.
What We Found: Key Patterns
The most frequently detected contaminants exceeding health guidelines across these cities are Total trihalomethanes (TTHMs), Dibromochloromethane, Haloacetic acids (HAA5). These appear repeatedly across different water systems and regions.
Geographically, the states most represented in this ranking are Texas (8), California (6), Kansas (4). Regional water sources, industrial activity, and agricultural runoff all contribute to local water quality variation.
Across all ranked cities, 215 contaminant readings exceed EWG health guidelines, but only 33 exceed EPA legal limits. This gap of 182 highlights how legal standards may not fully protect public health — EPA limits haven't been updated for many contaminants in decades.
Full Rankings Table
| Rank | City | State | Detected | Above Guidelines | Above Legal | People Served |
|---|---|---|---|---|---|---|
| 1 | Eola | TX | 12 | 8 | 1 | 165 |
| 2 | Aguanga | CA | 8 | 4 | 1 | 75 |
| 3 | Whitharral | TX | 13 | 10 | 1 | 200 |
| 4 | Edison | CA | 14 | 10 | 2 | 438 |
| 5 | Lemon Cove | CA | 10 | 10 | 2 | 109 |
| 6 | Morro Bay | CA | 26 | 15 | 1 | 10,581 |
| 7 | Turkey | TX | 13 | 9 | 1 | 421 |
| 8 | Ford | KS | 12 | 8 | 1 | 0 |
| 9 | Grantville | KS | 18 | 11 | 1 | 228 |
| 10 | Bent | TX | 14 | 10 | 2 | 120 |
| 11 | Okarche | OK | 10 | 9 | 1 | 1,110 |
| 12 | Quitaque | TX | 12 | 8 | 1 | 0 |
| 13 | Turner | MT | 6 | 3 | 1 | 50 |
| 14 | Iuka | KS | 14 | 10 | 1 | 155 |
| 15 | Little Diomede | AK | 11 | 10 | 2 | 0 |
| 16 | Orwell | NY | 12 | 10 | 1 | 150 |
| 17 | Welch | TX | 12 | 8 | 2 | 315 |
| 18 | Corcoran | CA | 26 | 16 | 1 | 21,835 |
| 19 | Lewistown | MT | 5 | 3 | 1 | 56 |
| 20 | Montezuma | IN | 5 | 3 | 1 | 1,022 |
| 21 | Barker | TX | 4 | 3 | 2 | 165 |
| 22 | Sylvia | KS | 14 | 8 | 1 | 210 |
| 23 | Lenorah | TX | 16 | 11 | 2 | 0 |
| 24 | Valley Ford | CA | 14 | 10 | 2 | 61 |
| 25 | Geary | OK | 11 | 8 | 1 | 1,258 |
Frequently Asked Questions
What cities have the highest levels of nitrate?
Our analysis of 2026 data identified the cities with the highest detected levels of nitrate. See the full ranking above.
Is nitrate dangerous in drinking water?
Nitrate has known health risks at elevated levels. The EWG sets health guidelines that are often stricter than EPA legal limits to account for the latest research on long-term exposure.
How do I remove nitrate from my water?
Reverse osmosis (RO) systems are the most effective at removing a wide range of contaminants. Check the specific contaminant details for recommended filtration technology.
What is the EPA legal limit for nitrate?
EPA legal limits vary by contaminant and may differ from EWG health guidelines. See individual city reports for specific legal limit comparisons.
Related Reports
Data sources: Environmental Working Group (EWG) Tap Water Database, U.S. EPA Safe Drinking Water Information System (SDWIS)
Last updated: September 2026
Methodology: Contaminant levels are compared against both EPA legal limits (Maximum Contaminant Levels) and EWG health guidelines, which are often stricter and based on the latest scientific research.
