Well water in Tom Green County, Texas
In Tom Green County, 66% of 58 tested well samples exceeded the EPA limit for nitrate (10 mg/L), based on public data from Texas Water Development Board Groundwater Database and USGS Water Quality Portal.
125 individual samples from 83 wells, 1967 to 2023. Data refreshed September 9, 2026.
TWDB samples an ambient monitoring network of wells on a rotation, so these describe aquifers, not a survey of homeowners' tests.
What individual samples found
Each row summarizes every public sample for that contaminant inside Tom Green County. Above limit means above the EPA maximum contaminant level; where EPA has no enforceable limit, the row shows a health guideline or nuisance level instead.
| Contaminant | Samples | Detected | Above limit | Median | Highest | Limit | |
|---|---|---|---|---|---|---|---|
| Nitrate 1983 to 2023 | 58 | 98% | 66% | 25.9 | 87.5 | 10 mg/L EPA limit | |
| Fluoride 1967 to 2023 | 122 | 98% | 0% | 0.7 | 2.4 | 4 mg/L EPA limit | |
| Arsenic 1983 to 2023 | 58 | 71% | 0% | 2.88 | 7.1 | 10 ug/L EPA limit | |
| Copper 1983 to 2023 | 57 | 65% | 0% | 0.003 | 0.028 | 1.3 mg/L EPA limit | |
| Lead 1983 to 2023 | 48 | 6% | 0% | 0 | 4 | 15 ug/L EPA limit | |
| Uranium 2010 to 2023 | 21 | 100% | 0% | 4 | 20.3 | 30 ug/L EPA limit | |
| Gross alpha 1992 to 2010 | 12 | 75% | 0% | 3.05 | 10.6 | 15 pCi/L EPA limit | |
| Chloride 1967 to 2023 | 125 | 100% | no limit | 300 | 1,670 | 250 mg/L nuisance level | |
| Sodium 1967 to 2023 | 125 | 100% | no limit | 138 | 600 | 20 mg/L health guideline | |
| Manganese 1983 to 2023 | 57 | 25% | no limit | 0 | 20 | 300 ug/L health guideline | |
| Iron 1983 to 2023 | 57 | 30% | no limit | 0 | 125 | 300 ug/L nuisance level |
Sampled fewer than 10 times, too few to summarize: Radium (226 + 228) (6), E. coli (1), Radon (1).
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What this means
The contaminants most often above their limit here are nitrate (66% of 58 samples). A well next door can differ sharply from yours because bedrock fractures, well depth and plumbing all matter, so these rates describe the area, not your tap.
Chloride is widespread in local groundwater. It is mainly a staining and taste problem, but high manganese also carries a health advisory for infants.
What to test for in Tom Green County
- Volatile organic compounds (VOCs)193 leaking underground storage tank sites on record locally.
- Metals panel1 hazardous waste site on record locally.
- Nitrate66% of 58 local samples were above the limit.
- Coliform bacteriaRecommended for every private well, every year.
- RadonMedian local reading is 520 pCi/L.
- ChlorideDetected in 100% of local samples.
- FluorideDetected in 98% of local samples.
- CopperDetected in 65% of local samples.
Contamination sources on record in Tom Green County
TCEQ records 193 leaking underground storage tank sites and 1 hazardous waste site in Tom Green County, among 212 regulated sites in total. Groundwater does not follow property lines, so a well within a few hundred feet of one of these is worth testing for what that site could release.
- 193
- leaking underground storage tank sitesGasoline and heating oil that leaked from tanks move through groundwater as benzene, MTBE and other volatile organic compounds.
- 1
- hazardous waste siteSolvents, degreasers and metals from industrial sites can travel far in fractured bedrock.
- 18
- lined landfills and transfer facilities
Treatment that fits the local profile
- Nitrate
- Point-of-use reverse osmosis; Anion exchange; Distillation
- Fluoride
- Point-of-use reverse osmosis; Activated alumina; Distillation
- Copper
- Neutralizing filter to raise pH; Point-of-use reverse osmosis
- Chloride
- Point-of-use reverse osmosis; Distillation
Get your Tom Green County water tested at home
A licensed local water treatment company tests your tap water in your home, walks you through the numbers, and quotes treatment only if something needs fixing. Free, about 30 minutes, no obligation. Tell us what you need and we match you with a company that serves Tom Green County.
Common questions
Is there arsenic in well water in Tom Green County?
Arsenic was detected in 71% of 58 public well samples in Tom Green County, and 0% were above the EPA limit of 10 ug/L. Arsenic has no taste or smell; a lab test is the only way to know your level.
How high is radon in well water in Tom Green County?
The median radon level across 1 public samples in Tom Green County was 520 pCi/L, with a high of 520 pCi/L. New Hampshire recommends treatment above 2,000 pCi/L.
How often should I test a private well in Tom Green County?
Test for bacteria and nitrate every year. Test once for arsenic, uranium, radon, fluoride, manganese and PFAS, then again every three to five years or after any change in taste, color, or plumbing.
Sources
- Texas Water Development Board Groundwater Database: 743 samples in Tom Green County. Water quality samples from the Texas Water Development Board Groundwater Database, collected by TWDB, groundwater conservation districts and cooperators. Retrieved September 9, 2026.
- USGS Water Quality Portal: 5 samples in Tom Green County. Data from the Water Quality Portal, a service of USGS, EPA and USDA; groundwater samples collected by USGS and cooperators. Retrieved September 3, 2026.
- TCEQ regulated sites: 212 regulated sites located in Tom Green County. Leaking petroleum storage tank sites, state Superfund sites and municipal solid waste landfills from the Texas Commission on Environmental Quality. Retrieved September 9, 2026.
Non-detects count as samples and are treated as zero when computing medians. Exactly at the limit counts as not above it. A sample belongs to the town containing the well's reported coordinates.