Well water in Texas
In Texas, 12% of 2,417 tested well samples exceeded the EPA limit for gross alpha (15 pCi/L), based on public data from Texas Water Development Board Groundwater Database and USGS Water Quality Portal.
24,914 individual samples from 15,339 wells, 1907 to 2026. 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. In that targeted sampling, 10% of 89 PFOS results in Texas were above the EPA limit of 4 ng/L. In that targeted sampling, 8% of 89 PFOA results in Texas were above the EPA limit of 4 ng/L.
What individual samples found
Each row summarizes every public sample for that contaminant inside Texas. 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 1972 to 2026 | 2,417 | 67% | 12% | 4.27 | 525 | 15 pCi/L EPA limit | |
| PFOS 2019 to 2025 | 89 | 22% | 10% | 0 | 170 | 4 ng/L EPA limit | |
| Nitrate 1936 to 2026 | 6,846 | 80% | 9% | 1.2 | 4,520 | 10 mg/L EPA limit | |
| Arsenic 1949 to 2026 | 6,543 | 38% | 9% | 0 | 569 | 10 ug/L EPA limit | |
| PFOA 2019 to 2025 | 89 | 16% | 8% | 0 | 670 | 4 ng/L EPA limit | |
| E. coli 2002 to 2021 | 415 | 5% | 5% | 0 | 140 | 0 MPN/100mL EPA limit | |
| Fluoride 1913 to 2026 | 20,190 | 97% | 4% | 0.7 | 168 | 4 mg/L EPA limit | |
| Radium (226 + 228) 1977 to 2026 | 3,605 | 59% | 2% | 0.23 | 147 | 5 pCi/L EPA limit | |
| Uranium 1980 to 2026 | 4,588 | 71% | 2% | 0.903 | 336 | 30 ug/L EPA limit | |
| Lead 1968 to 2026 | 6,238 | 8% | <1% | 0 | 115 | 15 ug/L EPA limit | |
| Copper 1968 to 2026 | 6,274 | 58% | 0% | 0.001 | 1.07 | 1.3 mg/L EPA limit | |
| Total coliform 2012 to 2017 | 13 | 0% | 0% | 0 | 0 | 0 MPN/100mL EPA limit | |
| Chloride 1907 to 2026 | 24,914 | 100% | no limit | 57.3 | 16,038 | 250 mg/L nuisance level | |
| Sodium 1907 to 2026 | 21,087 | 100% | no limit | 78 | 14,000 | 20 mg/L health guideline | |
| Iron 1911 to 2026 | 9,343 | 55% | no limit | 12.5 | 153,000 | 300 ug/L nuisance level | |
| Manganese 1949 to 2026 | 6,669 | 50% | no limit | 0 | 128,000 | 300 ug/L health guideline | |
| Radon 1990 to 2017 | 655 | 95% | no limit | 300 | 8,670 | 2,000 pCi/L health guideline |
Get the free Texas well report
One email with the numbers above, what they mean for a home in Texas, 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 gross alpha (12% of 2,417 samples), pfos (10% of 89 samples), and nitrate (9% of 6,846 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 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 Texas
- Volatile organic compounds (VOCs)28,717 leaking underground storage tank sites on record locally.
- Metals panel167 hazardous waste sites on record locally.
- Gross alpha12% of 2,417 local samples were above the limit.
- PFOS10% of 89 local samples were above the limit.
- Nitrate9% of 6,846 local samples were above the limit.
- Arsenic9% of 6,543 local samples were above the limit.
- PFOA8% of 89 local samples were above the limit.
- E. coli5% of 415 local samples were above the limit.
- Fluoride4% of 20,190 local samples were above the limit.
Contamination sources on record in Texas
TCEQ records 28,717 leaking underground storage tank sites and 167 hazardous waste sites in Texas, among 31,488 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.
- 28,717
- leaking underground storage tank sitesGasoline and heating oil that leaked from tanks move through groundwater as benzene, MTBE and other volatile organic compounds.
- 167
- hazardous waste sitesSolvents, degreasers and metals from industrial sites can travel far in fractured bedrock.
- 2,604
- 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
- PFOS
- Granular activated carbon whole-house; Point-of-use reverse osmosis; Anion exchange
- Nitrate
- Point-of-use reverse osmosis; Anion exchange; Distillation
- Arsenic
- Point-of-use reverse osmosis; Adsorptive media (iron-based) whole-house; Anion exchange
- PFOA
- Granular activated carbon whole-house; Point-of-use reverse osmosis; Anion exchange
Common questions
Is there arsenic in well water in Texas?
Arsenic was detected in 38% of 6,543 public well samples in Texas, and 9% 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 Texas?
The median radon level across 655 public samples in Texas was 300 pCi/L, with a high of 8,670 pCi/L. New Hampshire recommends treatment above 2,000 pCi/L.
How often should I test a private well in Texas?
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.
Counties in Texas
- Anderson0% fluoride
- Andrews24% fluoride
- Angelina0% fluoride
- Aransas36 samples
- Archer6% fluoride
- Armstrong3% radium (226 + 228)
- Atascosa4% radium (226 + 228)
- Austin0% fluoride
- Bandera11% fluoride
- Bastrop0% fluoride
- Baylor7% fluoride
- Bee<1% fluoride
- Bell28% fluoride
- Bexar11% e. coli
- Blanco3% radium (226 + 228)
- Bosque11% fluoride
- Bowie4% fluoride
- Brazoria0% fluoride
- Brazos0% fluoride
- Brewster2% fluoride
- Briscoe41% fluoride
- Brooks3% fluoride
- Brown2% fluoride
- Burleson0% arsenic
- Burnet2% nitrate
- Caldwell0% fluoride
- Calhoun0% fluoride
- Callahan<1% fluoride
- Cameron1% fluoride
- Carson3% arsenic
- Cass3% lead
- Chambers0% arsenic
- Cherokee0% fluoride
- Clay0% fluoride
- Coleman0% fluoride
- Colorado8% radium (226 + 228)
- Comal2% nitrate
- Comanche15% nitrate
- Concho0% fluoride
- Cooke0% fluoride
- Coryell22% fluoride
- Crockett0% arsenic
- Crosby12% arsenic
- Culberson8% arsenic
- Dallam12% fluoride
- Dawson91% arsenic
- Deaf Smith2% fluoride
- Denton4% fluoride
- DeWitt1% fluoride
- Dimmit3% fluoride
- Donley6% nitrate
- Duval50% arsenic
- Eastland0% fluoride
- Ector0% fluoride
- Edwards2% nitrate
- Ellis55 samples
- El Paso0% uranium
- Erath15% nitrate
- Fayette<1% fluoride
- Floyd17% arsenic
- Fort Bend0% fluoride
- Freestone0% fluoride
- Frio10% nitrate
- Gaines71% arsenic
- Galveston55 samples
- Gillespie6% gross alpha
- Glasscock27% nitrate
- Goliad16% arsenic
- Gonzales0% arsenic
- Gray0% arsenic
- Grayson0% fluoride
- Grimes0% fluoride
- Guadalupe2% fluoride
- Hale0% fluoride
- Hamilton1% fluoride
- Hansford0% arsenic
- Hardin9% radium (226 + 228)
- Harris2% uranium
- Harrison0% fluoride
- Hartley0% fluoride
- Haskell1% fluoride
- Hays6% fluoride
- Hemphill12% nitrate
- Henderson0% fluoride
- Hidalgo6% fluoride
- Hockley38% fluoride
- Hood0% fluoride
- Hopkins28% fluoride
- Houston0% fluoride
- Howard59% nitrate
- Hudspeth12% fluoride
- Hutchinson8% nitrate
- Irion0% fluoride
- Jack5% fluoride
- Jackson0% fluoride
- Jasper0% arsenic
- Jeff Davis0% fluoride
- Jefferson0% fluoride
- Jim Wells1% fluoride
- Johnson3% fluoride
- Jones3% fluoride
- Karnes0% fluoride
- Kendall3% fluoride
- Kerr1% fluoride
- Kimble11% nitrate
- Kinney0% fluoride
- Knox94% nitrate
- Lamb36% nitrate
- Lampasas0% fluoride
- La Salle0% arsenic
- Lavaca11% gross alpha
- Lee0% fluoride
- Leon0% fluoride
- Liberty2% radium (226 + 228)
- Limestone0% fluoride
- Lipscomb7% fluoride
- Live Oak30% gross alpha
- Llano0% fluoride
- Lubbock41% fluoride
- Lynn87% nitrate
- Madison0% fluoride
- Martin67% arsenic
- Mason18% nitrate
- Matagorda15% gross alpha
- McCulloch6% nitrate
- McMullen0% fluoride
- Medina3% radium (226 + 228)
- Menard0% fluoride
- Midland27% arsenic
- Milam0% fluoride
- Mills0% fluoride
- Mitchell10% fluoride
- Montague3% fluoride
- Montgomery7% radium (226 + 228)
- Moore6% nitrate
- Nacogdoches0% fluoride
- Newton0% fluoride
- Nolan0% fluoride
- Nueces0% fluoride
- Ochiltree2% arsenic
- Orange0% fluoride
- Palo Pinto7% fluoride
- Panola0% fluoride
- Parker1% fluoride
- Parmer0% fluoride
- Pecos8% nitrate
- Polk0% fluoride
- Potter5% arsenic
- Presidio31% arsenic
- Rains0% fluoride
- Randall3% fluoride
- Reagan13% radium (226 + 228)
- Real0% fluoride
- Red River2% fluoride
- Reeves3% fluoride
- Refugio0% fluoride
- Roberts<1% fluoride
- Robertson3% nitrate
- Rusk0% fluoride
- Sabine88 samples
- San Augustine0% fluoride
- San Jacinto0% fluoride
- San Patricio17% arsenic
- San Saba6% fluoride
- Schleicher2% nitrate
- Scurry19% nitrate
- Shackelford0% fluoride
- Shelby0% fluoride
- Sherman9% nitrate
- Smith0% fluoride
- Starr53% nitrate
- Stephens3% fluoride
- Sterling0% fluoride
- Sutton<1% nitrate
- Swisher19% fluoride
- Tarrant1% uranium
- Terrell0% arsenic
- Terry84% arsenic
- Titus0% fluoride
- Tom Green66% nitrate
- Travis11% fluoride
- Tyler0% fluoride
- Upshur0% fluoride
- Upton21% nitrate
- Uvalde5% fluoride
- Val Verde2% nitrate
- Van Zandt0% fluoride
- Victoria5% nitrate
- Walker56 samples
- Waller31 samples
- Ward0% fluoride
- Washington0% fluoride
- Webb12% arsenic
- Wharton3% gross alpha
- Wheeler0% fluoride
- Wilbarger0% fluoride
- Williamson25% fluoride
- Wilson0% uranium
- Winkler2% fluoride
- Wise3% nitrate
- Wood0% fluoride
- Yoakum71% arsenic
- Young<1% fluoride
- Zavala14% nitrate
50 counties have fewer than 30 public samples and are included in the Texas totals above rather than shown separately: Bailey, Borden, Camp, Castro, Childress, Cochran, Coke, Collin, Collingsworth, Cottle, Crane, Dallas, Delta, Dickens, Falls, Fannin, Fisher, Foard, Franklin, Garza, Gregg, Hall, Hardeman, Hill, Hunt, Jim Hogg, Kaufman, Kenedy, Kent, King, Kleberg, Lamar, Loving, Marion, Maverick, McLennan, Morris, Motley, Navarro, Oldham, Rockwall, Runnels, Somervell, Stonewall, Taylor, Throckmorton, Trinity, Wichita, Willacy, Zapata.
Sources
- Texas Water Development Board Groundwater Database: 114,431 samples in Texas. 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: 5,544 samples in Texas. 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: 31,488 regulated sites located in Texas. 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.