Well water in Grayson County, Texas
In Grayson County, none of 48 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.
50 individual samples from 17 wells, 1957 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 Grayson 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 | |
|---|---|---|---|---|---|---|---|
| Fluoride 1958 to 1993 | 48 | 96% | 0% | 0.9 | 2.7 | 4 mg/L EPA limit | |
| Chloride 1957 to 1993 | 50 | 100% | no limit | 14 | 1,050 | 250 mg/L nuisance level | |
| Sodium 1958 to 1993 | 48 | 100% | no limit | 180 | 966 | 20 mg/L health guideline | |
| Iron 1958 to 1993 | 19 | 84% | no limit | 120 | 2,800 | 300 ug/L nuisance level |
Sampled fewer than 10 times, too few to summarize: Radium (226 + 228) (6), Arsenic (3), Uranium (3), Lead (3), Copper (3), E. coli (3), Nitrate (2), Gross alpha (2), Manganese (9), Radon (3).
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What this means
Among contaminants with a federal limit, no tested sample in Grayson County came back above it. That is reassuring, but sampling is uneven: wells that were never tested are not in this data.
Chloride and Iron 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 Grayson County
- Volatile organic compounds (VOCs)163 leaking underground storage tank sites on record locally.
- Metals panel1 hazardous waste site on record locally.
- Coliform bacteriaRecommended for every private well, every year.
- RadonMedian local reading is 310 pCi/L.
- ChlorideDetected in 100% of local samples.
- NitrateRecommended for every private well, especially near farms or septic systems.
- FluorideDetected in 96% of local samples.
- IronDetected in 84% of local samples.
Contamination sources on record in Grayson County
TCEQ records 163 leaking underground storage tank sites and 1 hazardous waste site in Grayson County, among 189 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.
- 163
- 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.
- 25
- lined landfills and transfer facilities
Treatment that fits the local profile
- 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 Grayson 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 Grayson County.
Common questions
Is there arsenic in well water in Grayson County?
Arsenic was detected in 0% of 3 public well samples in Grayson 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 Grayson County?
The median radon level across 3 public samples in Grayson County was 310 pCi/L, with a high of 920 pCi/L. New Hampshire recommends treatment above 2,000 pCi/L.
How often should I test a private well in Grayson 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: 187 samples in Grayson 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: 15 samples in Grayson 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: 189 regulated sites located in Grayson 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.