Well water in Uvalde County, Texas
In Uvalde County, 5% of 42 tested well samples exceeded the EPA limit for fluoride (4 mg/L), based on public data from Texas Water Development Board Groundwater Database and USGS Water Quality Portal.
78 individual samples from 40 wells, 1930 to 2022. 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 Uvalde 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 | |
|---|---|---|---|---|---|---|---|
| E. coli 2004 to 2018 | 15 | 13% | 13% | 0 | 13 | 0 MPN/100mL EPA limit | |
| Fluoride 1956 to 2018 | 42 | 98% | 5% | 0.11 | 4.3 | 4 mg/L EPA limit | |
| Uranium 1996 to 2022 | 78 | 60% | 0% | 0.617 | 28.8 | 30 ug/L EPA limit | |
| Radium (226 + 228) 2006 to 2018 | 52 | 81% | 0% | 0.123 | 4.7 | 5 pCi/L EPA limit | |
| Arsenic 1979 to 2017 | 46 | 11% | 0% | 0 | 1 | 10 ug/L EPA limit | |
| Copper 1977 to 2009 | 34 | 65% | 0% | 0.002 | 0.012 | 1.3 mg/L EPA limit | |
| Nitrate 1978 to 2009 | 32 | 97% | 0% | 1.69 | 3.6 | 10 mg/L EPA limit | |
| Lead 1982 to 2018 | 31 | 19% | 0% | 0 | 3 | 15 ug/L EPA limit | |
| Sodium 1930 to 2009 | 43 | 100% | no limit | 7.31 | 61 | 20 mg/L health guideline | |
| Chloride 1930 to 2009 | 40 | 100% | no limit | 12 | 81 | 250 mg/L nuisance level | |
| Radon 1996 to 2017 | 35 | 91% | no limit | 290 | 1,040 | 2,000 pCi/L health guideline | |
| Iron 1954 to 2009 | 31 | 35% | no limit | 0 | 14,300 | 300 ug/L nuisance level | |
| Manganese 1981 to 2009 | 29 | 14% | no limit | 0 | 3 | 300 ug/L health guideline |
Sampled fewer than 10 times, too few to summarize: PFOA (4), PFOS (4), Gross alpha (1).
Get the free Uvalde County well report
One email with the numbers above, what they mean for a home in Uvalde County, exactly which tests to order, and what treatment fits the local profile. No spam, unsubscribe in one click.
What this means
The contaminants most often above their limit here are e. coli (13% of 15 samples) and fluoride (5% of 42 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 Uvalde County
- Volatile organic compounds (VOCs)57 leaking underground storage tank sites on record locally.
- E. coli13% of 15 local samples were above the limit.
- Fluoride5% of 42 local samples were above the limit.
- RadonMedian local reading is 290 pCi/L.
- ChlorideDetected in 100% of local samples.
- NitrateRecommended for every private well, especially near farms or septic systems.
- CopperDetected in 65% of local samples.
Contamination sources on record in Uvalde County
TCEQ records 57 leaking underground storage tank sites in Uvalde County, among 65 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.
- 57
- leaking underground storage tank sitesGasoline and heating oil that leaked from tanks move through groundwater as benzene, MTBE and other volatile organic compounds.
- 8
- lined landfills and transfer facilities
Treatment that fits the local profile
- E. coli
- Shock chlorination and fix the well cap or casing; UV disinfection whole-house; Chlorination system
- 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 Uvalde 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 Uvalde County.
Common questions
Is there arsenic in well water in Uvalde County?
Arsenic was detected in 11% of 46 public well samples in Uvalde 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 Uvalde County?
The median radon level across 35 public samples in Uvalde County was 290 pCi/L, with a high of 1,040 pCi/L. New Hampshire recommends treatment above 2,000 pCi/L.
How often should I test a private well in Uvalde 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: 296 samples in Uvalde 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: 221 samples in Uvalde 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: 65 regulated sites located in Uvalde 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.