Well water in Kendall County, Texas
In Kendall County, 3% of 110 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.
149 individual samples from 119 wells, 1940 to 2011. 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 Kendall 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 1994 to 2011 | 18 | 72% | 6% | 0.08 | 48.2 | 10 mg/L EPA limit | |
| Radium (226 + 228) 1994 to 2011 | 22 | 73% | 5% | 0.7 | 5.3 | 5 pCi/L EPA limit | |
| Fluoride 1940 to 2011 | 110 | 100% | 3% | 1.4 | 5.1 | 4 mg/L EPA limit | |
| Arsenic 1990 to 2011 | 21 | 10% | 0% | 0 | 2 | 10 ug/L EPA limit | |
| Lead 1994 to 2011 | 19 | 26% | 0% | 0 | 3.4 | 15 ug/L EPA limit | |
| Copper 1994 to 2011 | 18 | 28% | 0% | 0 | 0.008 | 1.3 mg/L EPA limit | |
| Gross alpha 1994 to 2011 | 11 | 45% | 0% | 0 | 6.2 | 15 pCi/L EPA limit | |
| Uranium 1996 to 2011 | 11 | 27% | 0% | 0 | 2 | 30 ug/L EPA limit | |
| Chloride 1940 to 2011 | 149 | 100% | no limit | 37 | 487 | 250 mg/L nuisance level | |
| Sodium 1940 to 2011 | 146 | 99% | no limit | 26 | 449 | 20 mg/L health guideline | |
| Iron 1966 to 2011 | 22 | 77% | no limit | 82.8 | 3,400 | 300 ug/L nuisance level | |
| Manganese 1994 to 2011 | 18 | 83% | no limit | 3.7 | 19.5 | 300 ug/L health guideline | |
| Radon 1990 to 1996 | 11 | 91% | no limit | 360 | 560 | 2,000 pCi/L health guideline |
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What this means
The contaminants most often above their limit here are nitrate (6% of 18 samples), radium (226 + 228) (5% of 22 samples), and fluoride (3% of 110 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 Kendall County
- Volatile organic compounds (VOCs)22 leaking underground storage tank sites on record locally.
- Nitrate6% of 18 local samples were above the limit.
- Radium (226 + 228)5% of 22 local samples were above the limit.
- Fluoride3% of 110 local samples were above the limit.
- Coliform bacteriaRecommended for every private well, every year.
- RadonMedian local reading is 360 pCi/L.
- ChlorideDetected in 100% of local samples.
- ManganeseDetected in 83% of local samples.
Contamination sources on record in Kendall County
TCEQ records 22 leaking underground storage tank sites in Kendall County, among 27 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.
- 22
- leaking underground storage tank sitesGasoline and heating oil that leaked from tanks move through groundwater as benzene, MTBE and other volatile organic compounds.
- 5
- 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 Kendall 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 Kendall County.
Common questions
Is there arsenic in well water in Kendall County?
Arsenic was detected in 10% of 21 public well samples in Kendall 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 Kendall County?
The median radon level across 11 public samples in Kendall County was 360 pCi/L, with a high of 560 pCi/L. New Hampshire recommends treatment above 2,000 pCi/L.
How often should I test a private well in Kendall 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: 564 samples in Kendall 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: 12 samples in Kendall 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: 27 regulated sites located in Kendall 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.