Nitrate in Texas well water
In Texas, 9% of 19,663 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.
Test your Texas well for nitrate
Certified lab analysis of your own tap water, bottles and prepaid return shipping included. The Essential well panel covers arsenic, uranium, nitrate, lead, copper, manganese, iron, sodium and bacteria; radon and PFAS are add-ons.
Order the Tap Score well water test kit, from $209Already tested? Upload the report
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Systems that remove nitrate
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Some links below are affiliate links. If you buy through one, the merchant pays us a commission at no extra cost to you. It does not change which products we list or what the data says.
For nitrate
Under-sink reverse osmosis system
under-sink or countertop, about $300
Look for NSF/ANSI 58 certification listing the contaminant you need removed.
For nitrate
Aquasana SmartFlow reverse osmosis
under-sink or countertop, about $225
Certified to NSF/ANSI 58 and 53 to reduce arsenic (96%, pentavalent), fluoride (90%), lead (99%), nitrate, nitrite and PFOA/PFOS at the kitchen tap, with a remineralizer.
Rather have it installed and sized for your well? Book a free in-home water test with a licensed local company.
Where to get a well tested for nitrate in Texas: certified labs, state programs and prices.
By county, from individual samples
Public monitoring samples against the EPA limit (10 mg/L); counties with at least 30 samples.
| County | Above EPA limit | Samples | Detected | Median | Highest |
|---|---|---|---|---|---|
| Lynn | 42 | 100% | 19.8 | 67.1 mg/L | |
| Knox | 127 | 97% | 17.2 | 186 mg/L | |
| Navarro | 34 | 94% | 29 | 567 mg/L | |
| Tom Green | 82 | 98% | 21 | 87.5 mg/L | |
| Starr | 34 | 97% | 10.3 | 79.4 mg/L | |
| Martin | 84 | 100% | 10.7 | 86.3 mg/L | |
| Howard | 70 | 94% | 9.74 | 107 mg/L | |
| Terry | 78 | 96% | 9.65 | 98.2 mg/L | |
| Duval | 170 | 99% | 7.17 | 363 mg/L | |
| Washington | 121 | 95% | 5 | 916 mg/L | |
| Jefferson | 75 | 73% | 1.8 | 199 mg/L | |
| Caldwell | 242 | 97% | 2 | 575 mg/L | |
| Dawson | 75 | 100% | 7.03 | 75.6 mg/L | |
| Guadalupe | 106 | 91% | 1.8 | 4,520 mg/L | |
| Bee | 141 | 97% | 3.36 | 544 mg/L |
- East Tom Green CCD, Tom Green County88% of 48
- Seguin CCD, Guadalupe County71% of 35
- Benjamin CCD, Knox County64% of 81
- Big Spring North CCD, Howard County61% of 41
- Brownfield CCD, Terry County56% of 55
- Lockhart CCD, Caldwell County55% of 111
- Brenham CCD, Washington County54% of 35
- Realitos-Concepcion CCD, Duval County54% of 65
- Tarzan-Lenorah CCD, Martin County52% of 63
- Benavides CCD, Duval County51% of 41
- Encino CCD, Brooks County42% of 88
- Nome-China CCD, Jefferson County41% of 41
- Beeville CCD, Bee County41% of 66
- Burton CCD, Washington County39% of 36
- Dublin CCD, Erath County36% of 33
- Littlefield CCD, Lamb County33% of 30
- Garden City South CCD, Glasscock County33% of 51
- Pettus-Pawnee CCD, Bee County33% of 52
- Washington-Chappell Hill CCD, Washington County32% of 34
- San Diego CCD, Duval County30% of 33
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.
Analysis: Nitrate in private wells, decade by decade, from the same public records.