Well water in Carson County, Texas
In Carson County, 3% of 59 tested well samples exceeded the EPA limit for arsenic (10 ug/L), based on public data from Texas Water Development Board Groundwater Database and USGS Water Quality Portal.
542 individual samples from 67 wells, 1938 to 2021. 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 Carson 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 | |
|---|---|---|---|---|---|---|---|
| Gross alpha 1991 to 2012 | 23 | 96% | 4% | 7.48 | 16 | 15 pCi/L EPA limit | |
| Arsenic 1991 to 2021 | 59 | 78% | 3% | 2.39 | 12.9 | 10 ug/L EPA limit | |
| Fluoride 1981 to 2021 | 540 | 100% | 3% | 1.2 | 168 | 4 mg/L EPA limit | |
| Nitrate 1991 to 2021 | 58 | 100% | 0% | 1.55 | 7.6 | 10 mg/L EPA limit | |
| Copper 1991 to 2021 | 58 | 62% | 0% | 0.001 | 0.023 | 1.3 mg/L EPA limit | |
| Lead 1991 to 2021 | 57 | 12% | 0% | 0 | 1.85 | 15 ug/L EPA limit | |
| Radium (226 + 228) 1999 to 2021 | 42 | 40% | 0% | 0 | 1 | 5 pCi/L EPA limit | |
| Uranium 1999 to 2021 | 25 | 100% | 0% | 5.7 | 10.1 | 30 ug/L EPA limit | |
| Chloride 1938 to 2021 | 542 | 100% | no limit | 13 | 588 | 250 mg/L nuisance level | |
| Sodium 1938 to 2021 | 60 | 100% | no limit | 22.9 | 315 | 20 mg/L health guideline | |
| Manganese 1991 to 2021 | 59 | 42% | no limit | 0 | 13.4 | 300 ug/L health guideline | |
| Iron 1991 to 2021 | 57 | 44% | no limit | 0 | 1,070 | 300 ug/L nuisance level |
Sampled fewer than 10 times, too few to summarize: E. coli (2), PFOS (1), PFOA (1), Radon (7).
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What this means
The contaminants most often above their limit here are gross alpha (4% of 23 samples), arsenic (3% of 59 samples), and fluoride (3% of 540 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 Carson County
- Volatile organic compounds (VOCs)29 leaking underground storage tank sites on record locally.
- Metals panel1 hazardous waste site on record locally.
- Gross alpha4% of 23 local samples were above the limit.
- Arsenic3% of 59 local samples were above the limit.
- Fluoride3% of 540 local samples were above the limit.
- Coliform bacteriaRecommended for every private well, every year.
- RadonMedian local reading is 350 pCi/L.
- ChlorideDetected in 100% of local samples.
- NitrateRecommended for every private well, especially near farms or septic systems.
Contamination sources on record in Carson County
TCEQ records 29 leaking underground storage tank sites and 1 hazardous waste site in Carson County, among 34 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.
- 29
- 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.
- 4
- lined landfills and transfer facilities
Treatment that fits the local profile
- Gross alpha
- Point-of-use reverse osmosis; Water softener (cation exchange) for radium; Anion exchange for uranium
- Arsenic
- Point-of-use reverse osmosis; Adsorptive media (iron-based) whole-house; Anion exchange
- 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 Carson 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 Carson County.
Common questions
Is there arsenic in well water in Carson County?
Arsenic was detected in 78% of 59 public well samples in Carson County, and 3% 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 Carson County?
The median radon level across 7 public samples in Carson County was 350 pCi/L, with a high of 1,440 pCi/L. New Hampshire recommends treatment above 2,000 pCi/L.
How often should I test a private well in Carson 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: 1,560 samples in Carson 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: 31 samples in Carson 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: 34 regulated sites located in Carson 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.