Well water in Llano County, Texas
In Llano County, none of 39 tested well samples exceeded the EPA limit for fluoride, based on public data from Texas Water Development Board Groundwater Database.
39 individual samples from 19 wells, 1959 to 2008. 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 Llano 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 1988 to 2008 | 14 | 100% | 79% | 24.3 | 60.8 | 15 pCi/L EPA limit | |
| Nitrate 1988 to 2008 | 10 | 100% | 60% | 10.8 | 24.5 | 10 mg/L EPA limit | |
| Fluoride 1959 to 2008 | 39 | 100% | 0% | 0.5 | 1.7 | 4 mg/L EPA limit | |
| Arsenic 1988 to 2008 | 11 | 0% | 0% | 0 | 0 | 10 ug/L EPA limit | |
| Copper 1988 to 2008 | 10 | 20% | 0% | 0 | 0.016 | 1.3 mg/L EPA limit | |
| Chloride 1959 to 2008 | 39 | 100% | no limit | 47 | 215 | 250 mg/L nuisance level | |
| Sodium 1959 to 2008 | 39 | 100% | no limit | 29 | 161 | 20 mg/L health guideline | |
| Iron 1972 to 2008 | 19 | 42% | no limit | 0 | 1,140 | 300 ug/L nuisance level | |
| Manganese 1988 to 2008 | 11 | 27% | no limit | 0 | 20 | 300 ug/L health guideline |
Sampled fewer than 10 times, too few to summarize: Radium (226 + 228) (5), Lead (7), Uranium (1).
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What this means
The contaminants most often above their limit here are gross alpha (79% of 14 samples) and nitrate (60% of 10 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 Llano County
- Volatile organic compounds (VOCs)32 leaking underground storage tank sites on record locally.
- Metals panel1 hazardous waste site on record locally.
- Gross alpha79% of 14 local samples were above the limit.
- Nitrate60% of 10 local samples were above the limit.
- Coliform bacteriaRecommended for every private well, every year.
- Radium (226 + 228)Above the limit in 3 of 5 local samples; too few to quote a rate.
- FluorideDetected in 100% of local samples.
- ChlorideDetected in 100% of local samples.
Contamination sources on record in Llano County
TCEQ records 32 leaking underground storage tank sites and 1 hazardous waste site in Llano County, among 44 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.
- 32
- 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.
- 11
- 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
- Nitrate
- Point-of-use reverse osmosis; Anion exchange; Distillation
- Fluoride
- Point-of-use reverse osmosis; Activated alumina; Distillation
- Chloride
- Point-of-use reverse osmosis; Distillation
Get your Llano 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 Llano County.
Common questions
Is there arsenic in well water in Llano County?
Arsenic was detected in 0% of 11 public well samples in Llano 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 often should I test a private well in Llano 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: 205 samples in Llano County. Water quality samples from the Texas Water Development Board Groundwater Database, collected by TWDB, groundwater conservation districts and cooperators. Retrieved September 9, 2026.
- TCEQ regulated sites: 44 regulated sites located in Llano 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.