Nitrate in Texas well water
In Texas, 9% of 6,846 tested private well samples exceeded the EPA limit for nitrate (10 mg/L).
Nitrate reaches wells from fertilizer, septic systems and manure. Above the limit it can cause methemoglobinemia (blue baby syndrome) in infants under six months, and long-term exposure is associated with some cancers. Shallow and dug wells near farmland or dense septic systems are most at risk.
Check your nitrate number
Type the value from your lab report. It is compared to the EPA limit, the same way the full interpretation does it.
Getting it fixed
Book a free in-home water test with a licensed local company, or see the treatment guide for what removes nitrate.
By county, from individual samples
Public monitoring samples against the EPA limit (10 mg/L); counties with at least 30 samples.
| County | Samples | Detected | Above EPA limit | Median | Highest |
|---|---|---|---|---|---|
| Knox | 52 | 100% | 94% | 18 | 63.3 mg/L |
| Lynn | 39 | 100% | 87% | 20.8 | 67.1 mg/L |
| Tom Green | 58 | 98% | 66% | 25.9 | 87.5 mg/L |
| Howard | 41 | 100% | 59% | 13.4 | 107 mg/L |
| Starr | 34 | 97% | 53% | 10.3 | 79.4 mg/L |
| Martin | 71 | 100% | 52% | 11.4 | 34.8 mg/L |
| Dawson | 68 | 100% | 37% | 7.04 | 75.6 mg/L |
| Lamb | 33 | 100% | 36% | 7.04 | 16.1 mg/L |
| Glasscock | 83 | 100% | 27% | 6.01 | 46.2 mg/L |
| Yoakum | 63 | 100% | 22% | 4.74 | 33.9 mg/L |
| Upton | 47 | 100% | 21% | 6.41 | 48.0 mg/L |
| Scurry | 31 | 65% | 19% | 1.62 | 18.3 mg/L |
| Midland | 66 | 100% | 18% | 5.83 | 38.8 mg/L |
| Mason | 50 | 94% | 18% | 2.56 | 42.5 mg/L |
| Erath | 123 | 72% | 15% | 0.6 | 49 mg/L |
- East Tom Green CCD, Tom Green County86% of 42
- Big Spring North CCD, Howard County64% of 33
- Tarzan-Lenorah CCD, Martin County52% of 58
- Dublin CCD, Erath County36% of 33
- Garden City South CCD, Glasscock County33% of 51
- Plains CCD, Yoakum County21% of 47
- Mason West CCD, Mason County21% of 34
- Midland South CCD, Midland County19% of 58
- Comanche CCD, Comanche County19% of 48
- Rankin CCD, Upton County18% of 40
- Canadian South CCD, Hemphill County17% of 30
- Garden City North CCD, Glasscock County16% of 32
- Big Lake CCD, Reagan County10% of 58
- Stratford CCD, Sherman County10% of 31
- Pearsall CCD, Frio County8% of 59
- Stephenville CCD, Erath County8% of 38
- Fort Stockton CCD, Pecos County5% of 39
- George West CCD, Live Oak County5% of 44
- Blanco CCD, Blanco County4% of 79
- Burnet CCD, Burnet County3% of 30
Sources
- Individual samples from the USGS Water Quality Portal and state monitoring, summarized per geography. nitrate counts and shares are listed on each county and town page with their sources.