Well water in Jefferson County, Texas
In Jefferson County, none of 49 tested well samples exceeded the EPA limit for fluoride, based on public data from Texas Water Development Board Groundwater Database and USGS Water Quality Portal.
128 individual samples from 101 wells, 1907 to 2017. 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 Jefferson 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 1992 to 2017 | 11 | 9% | 9% | 0 | 24.7 | 10 mg/L EPA limit | |
| Radium (226 + 228) 2005 to 2013 | 16 | 81% | 6% | 0.208 | 11.4 | 5 pCi/L EPA limit | |
| Fluoride 1941 to 2017 | 49 | 96% | 0% | 0.33 | 1.7 | 4 mg/L EPA limit | |
| Lead 1988 to 2017 | 14 | 14% | 0% | 0 | 0.12 | 15 ug/L EPA limit | |
| Copper 1988 to 2017 | 14 | 50% | 0% | 0.001 | 0.005 | 1.3 mg/L EPA limit | |
| Arsenic 1988 to 2017 | 13 | 15% | 0% | 0 | 2.47 | 10 ug/L EPA limit | |
| Uranium 2005 to 2017 | 10 | 0% | 0% | 0 | 0 | 30 ug/L EPA limit | |
| Chloride 1907 to 2017 | 128 | 100% | no limit | 140 | 1,700 | 250 mg/L nuisance level | |
| Sodium 1907 to 2017 | 79 | 100% | no limit | 218 | 1,030 | 20 mg/L health guideline | |
| Iron 1966 to 2017 | 32 | 97% | no limit | 335 | 2,381 | 300 ug/L nuisance level | |
| Manganese 1988 to 2017 | 13 | 100% | no limit | 165 | 201 | 300 ug/L health guideline |
Sampled fewer than 10 times, too few to summarize: E. coli (5), Gross alpha (4), Radon (5).
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What this means
The contaminants most often above their limit here are nitrate (9% of 11 samples) and radium (226 + 228) (6% of 16 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, Iron, and Manganese are widespread in local groundwater. They are mainly a staining and taste problem, but high manganese also carries a health advisory for infants.
What to test for in Jefferson County
- Volatile organic compounds (VOCs)598 leaking underground storage tank sites on record locally.
- Metals panel5 hazardous waste sites on record locally.
- Nitrate9% of 11 local samples were above the limit.
- Radium (226 + 228)6% of 16 local samples were above the limit.
- Coliform bacteriaRecommended for every private well, every year.
- RadonMedian local reading is 190 pCi/L.
- ChlorideDetected in 100% of local samples.
- ManganeseDetected in 100% of local samples.
- IronDetected in 97% of local samples.
Contamination sources on record in Jefferson County
TCEQ records 598 leaking underground storage tank sites and 5 hazardous waste sites in Jefferson County, among 616 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.
- 598
- leaking underground storage tank sitesGasoline and heating oil that leaked from tanks move through groundwater as benzene, MTBE and other volatile organic compounds.
- 5
- hazardous waste sitesSolvents, degreasers and metals from industrial sites can travel far in fractured bedrock.
- 13
- lined landfills and transfer facilities
Treatment that fits the local profile
- Nitrate
- Point-of-use reverse osmosis; Anion exchange; Distillation
- Radium (226 + 228)
- Water softener (cation exchange); Point-of-use reverse osmosis
- Fluoride
- Point-of-use reverse osmosis; Activated alumina; Distillation
- Chloride
- Point-of-use reverse osmosis; Distillation
- Iron
- Oxidizing filter whole-house; Water softener (low levels); Aeration plus filtration
Get your Jefferson 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 Jefferson County.
Common questions
Is there arsenic in well water in Jefferson County?
Arsenic was detected in 15% of 13 public well samples in Jefferson 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 Jefferson County?
The median radon level across 5 public samples in Jefferson County was 190 pCi/L, with a high of 240 pCi/L. New Hampshire recommends treatment above 2,000 pCi/L.
How often should I test a private well in Jefferson 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: 366 samples in Jefferson 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: 27 samples in Jefferson 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: 616 regulated sites located in Jefferson 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.