Quick answer
About 1,651,000 people in Texas (6.6% of residents) got their water from private wells in 2010, according to USGS estimates. Texas Groundwater Protection Committee runs the state’s private well guidance. Texas A&M AgriLife Extension's Texas Well Owner Network, funded through a Clean Water Act grant, holds local well-water screenings for total coliform, E. coli, nitrate-nitrogen and salinity at $15 per sample as of 2026.
- People on private wells
- 1,650,671
- Share of residents
- 6.6%
- Rank among states
- 7th
- Well users modeled above 10 µg/L arsenic
- 6.5%
Where to get your well tested in Texas
- Texas Groundwater Protection Committee: Private Wells, the state’s guidance for private well owners.
- Well water testing in Texas: what to test for and how to collect a sample.
- Certified laboratories in Texas. Use a lab certified for drinking water, so results are reliable.
Free or low-cost testing
Texas A&M AgriLife Extension's Texas Well Owner Network, funded through a Clean Water Act grant, holds local well-water screenings for total coliform, E. coli, nitrate-nitrogen and salinity at $15 per sample as of 2026. (source)
Mail-in lab kits are another option when no local lab is convenient. See well water test kits for what home kits can and can’t tell you.
What to test for
- Every year: total coliform bacteria and nitrate.
- Before buying equipment: pH, hardness, iron, manganese and, if there’s a smell, hydrogen sulfide.
- Based on location: arsenic, uranium and radon, PFAS, and lead in older plumbing.
USGS modeling estimates that about 6.5% of Texas’s private well users have water above the 10 µg/L arsenic limit. Arsenic has no taste or smell, so include it in your first test.
Private wells by county
Estimated people relying on private wells in each Texas county in 2010, the share of residents that represents, and the modeled share of well users with arsenic above 10 µg/L. These are USGS model estimates (2010 population), not measurements of any well. Arsenic is hidden for counties with fewer than 500 well users.
| County | People on wells | Share | Arsenic >10 µg/L |
|---|---|---|---|
| Harris County | 99,300 | 2.4% | 2.6% |
| Brazoria County | 55,546 | 17.7% | 2.8% |
| Montgomery County | 48,556 | 10.7% | 1.6% |
| Fort Bend County | 36,971 | 6.3% | 2.3% |
| Parker County | 35,392 | 30.3% | 2.7% |
| Lubbock County | 31,544 | 11.3% | 38.2% |
| Ector County | 30,722 | 22.4% | 23.7% |
| Liberty County | 30,215 | 39.9% | 2.0% |
| Orange County | 29,565 | 36.1% | 1.0% |
| Wise County | 28,956 | 49.0% | 2.9% |
| Bexar County | 27,082 | 1.6% | 1.8% |
| Comal County | 24,505 | 22.6% | 1.3% |
Show all 254 counties
| Midland County | 24,310 | 17.8% | 25.4% |
| Hays County | 21,073 | 13.4% | 1.0% |
| Bowie County | 20,876 | 22.6% | 1.2% |
| Tarrant County | 19,531 | 1.1% | 3.0% |
| Denton County | 18,165 | 2.7% | 1.6% |
| Wharton County | 17,727 | 42.9% | 3.6% |
| Victoria County | 17,600 | 20.3% | 5.7% |
| El Paso County | 16,998 | 2.1% | 29.3% |
| Waller County | 16,485 | 38.2% | 2.0% |
| Hardin County | 16,333 | 29.9% | 1.0% |
| Jasper County | 16,020 | 44.9% | 1.0% |
| Cass County | 15,927 | 52.3% | 1.4% |
| Williamson County | 15,808 | 3.7% | 1.1% |
| Erath County | 15,401 | 40.6% | 2.4% |
| Kendall County | 15,102 | 45.2% | 1.0% |
| Washington County | 14,656 | 43.5% | 2.0% |
| Austin County | 14,654 | 51.6% | 2.3% |
| Travis County | 14,529 | 1.4% | 1.5% |
| Burnet County | 14,405 | 33.7% | 1.8% |
| Randall County | 14,174 | 11.7% | 3.2% |
| Galveston County | 14,072 | 4.8% | 3.8% |
| Grimes County | 14,046 | 52.8% | 2.0% |
| Bee County | 13,600 | 42.7% | 37.3% |
| Bandera County | 13,068 | 63.8% | 1.2% |
| Hidalgo County | 12,900 | 1.7% | 30.3% |
| Walker County | 12,620 | 18.6% | 2.0% |
| Van Zandt County | 12,613 | 24.0% | 1.9% |
| Harrison County | 12,500 | 19.0% | 1.1% |
| Gillespie County | 12,271 | 49.4% | 2.0% |
| Jim Wells County | 12,136 | 29.7% | 39.0% |
| Atascosa County | 12,087 | 26.9% | 2.5% |
| Cameron County | 11,874 | 2.9% | 7.4% |
| Potter County | 11,637 | 9.6% | 4.7% |
| Henderson County | 11,463 | 14.6% | 1.8% |
| Smith County | 11,043 | 5.3% | 1.9% |
| Kerr County | 10,674 | 21.5% | 1.0% |
| Tom Green County | 10,548 | 9.6% | 3.0% |
| Fayette County | 10,192 | 41.5% | 2.8% |
| Lavaca County | 10,124 | 52.6% | 4.1% |
| San Jacinto County | 10,024 | 38.0% | 1.4% |
| Colorado County | 9,901 | 47.4% | 3.9% |
| Medina County | 9,768 | 21.2% | 2.7% |
| Guadalupe County | 9,407 | 7.2% | 2.8% |
| Johnson County | 9,381 | 6.2% | 3.0% |
| Hood County | 9,167 | 17.9% | 1.7% |
| Grayson County | 9,048 | 7.5% | 1.9% |
| Polk County | 8,884 | 19.6% | 1.9% |
| Brazos County | 8,764 | 4.5% | 2.0% |
| Chambers County | 8,516 | 24.3% | 3.2% |
| Matagorda County | 8,460 | 23.1% | 2.9% |
| Upshur County | 8,366 | 21.3% | 1.7% |
| Wilson County | 8,328 | 19.4% | 2.7% |
| San Patricio County | 7,777 | 12.0% | 15.6% |
| Nueces County | 7,620 | 2.2% | 15.0% |
| Newton County | 7,603 | 52.6% | 1.0% |
| Tyler County | 7,573 | 34.8% | 1.5% |
| Montague County | 7,571 | 38.4% | 4.4% |
| Cooke County | 7,535 | 19.6% | 1.6% |
| DeWitt County | 7,437 | 37.0% | 6.7% |
| Dallas County | 7,374 | 0.3% | 6.9% |
| Gaines County | 7,271 | 41.5% | 60.7% |
| Hale County | 7,034 | 19.4% | 6.4% |
| Bastrop County | 6,746 | 9.1% | 1.9% |
| Panola County | 6,686 | 28.1% | 1.7% |
| Bell County | 6,569 | 2.1% | 1.6% |
| Rusk County | 6,427 | 12.1% | 1.1% |
| Titus County | 6,394 | 19.8% | 2.0% |
| Comanche County | 6,277 | 44.9% | 4.7% |
| Blanco County | 6,063 | 57.8% | 1.5% |
| Anderson County | 5,987 | 10.2% | 1.5% |
| Leon County | 5,853 | 34.8% | 1.6% |
| Angelina County | 5,784 | 6.7% | 1.4% |
| Madison County | 5,574 | 40.8% | 2.0% |
| Wood County | 5,565 | 13.3% | 1.7% |
| Cherokee County | 5,548 | 10.9% | 1.2% |
| Callahan County | 5,534 | 40.9% | 2.0% |
| Shelby County | 5,494 | 21.6% | 2.0% |
| Hockley County | 5,355 | 23.4% | 40.5% |
| Uvalde County | 5,302 | 20.1% | 2.2% |
| Somervell County | 5,242 | 61.7% | 2.0% |
| Houston County | 5,199 | 21.9% | 1.8% |
| Jefferson County | 5,044 | 2.0% | 1.0% |
| Scurry County | 5,031 | 29.7% | 15.2% |
| Jackson County | 4,935 | 35.1% | 4.2% |
| Frio County | 4,920 | 28.6% | 3.0% |
| Burleson County | 4,918 | 28.6% | 2.3% |
| Live Oak County | 4,863 | 42.2% | 21.5% |
| Marion County | 4,849 | 46.0% | 1.4% |
| Jack County | 4,822 | 53.3% | 9.2% |
| Goliad County | 4,734 | 65.7% | 13.7% |
| Howard County | 4,590 | 13.1% | 12.1% |
| Llano County | 4,576 | 23.7% | 4.0% |
| Nacogdoches County | 4,378 | 6.8% | 1.3% |
| Coryell County | 4,317 | 5.7% | 1.1% |
| Karnes County | 4,164 | 28.1% | 9.7% |
| Morris County | 4,121 | 31.9% | 2.0% |
| Gonzales County | 4,031 | 20.4% | 2.0% |
| San Augustine County | 3,954 | 44.6% | 1.5% |
| Ellis County | 3,951 | 2.6% | 2.7% |
| Andrews County | 3,909 | 26.4% | 72.1% |
| Hamilton County | 3,892 | 45.7% | 1.0% |
| Bosque County | 3,852 | 21.2% | 1.0% |
| Caldwell County | 3,840 | 10.1% | 2.3% |
| Limestone County | 3,736 | 16.0% | 2.0% |
| Robertson County | 3,674 | 22.1% | 2.0% |
| Palo Pinto County | 3,607 | 12.8% | 6.5% |
| Aransas County | 3,559 | 15.4% | 8.3% |
| Lampasas County | 3,555 | 18.1% | 2.0% |
| McLennan County | 3,469 | 1.5% | 1.8% |
| Deaf Smith County | 3,436 | 17.7% | 4.9% |
| Gregg County | 3,399 | 2.8% | 1.5% |
| Pecos County | 3,321 | 21.4% | 4.0% |
| Camp County | 3,274 | 26.4% | 2.0% |
| Calhoun County | 3,205 | 15.0% | 6.6% |
| Kaufman County | 3,153 | 3.1% | 1.7% |
| Milam County | 3,117 | 12.6% | 1.1% |
| Dawson County | 3,047 | 22.0% | 82.5% |
| Fannin County | 3,044 | 9.0% | 2.0% |
| Sabine County | 3,041 | 28.1% | 1.0% |
| Eastland County | 3,003 | 16.2% | 4.0% |
| Lee County | 2,942 | 17.7% | 1.7% |
| Gray County | 2,914 | 12.9% | 3.0% |
| Duval County | 2,793 | 23.7% | 36.2% |
| Mills County | 2,748 | 55.7% | 3.0% |
| Kleberg County | 2,710 | 8.5% | 14.6% |
| Parmer County | 2,710 | 26.4% | 14.6% |
| Hunt County | 2,675 | 3.1% | 2.7% |
| Swisher County | 2,644 | 33.7% | 3.2% |
| Val Verde County | 2,526 | 5.2% | 2.4% |
| Terry County | 2,504 | 19.8% | 60.7% |
| Dimmit County | 2,485 | 24.9% | 3.8% |
| Clay County | 2,470 | 23.0% | 12.4% |
| Taylor County | 2,446 | 1.9% | 3.0% |
| Lamar County | 2,381 | 4.8% | 1.8% |
| Lynn County | 2,376 | 40.2% | 31.5% |
| Freestone County | 2,369 | 12.0% | 2.0% |
| Brown County | 2,302 | 6.0% | 2.1% |
| Lamb County | 2,301 | 16.5% | 21.5% |
| Hopkins County | 2,231 | 6.3% | 2.0% |
| Martin County | 2,227 | 46.4% | 35.8% |
| Collin County | 2,205 | 0.3% | 2.3% |
| Webb County | 2,184 | 0.9% | 9.3% |
| Red River County | 2,130 | 16.6% | 2.0% |
| San Saba County | 2,105 | 34.3% | 3.8% |
| Jim Hogg County | 2,098 | 39.6% | 34.8% |
| Real County | 2,057 | 62.2% | 1.0% |
| Castro County | 2,018 | 25.0% | 4.3% |
| Hill County | 2,015 | 5.7% | 2.2% |
| Kimble County | 1,970 | 42.8% | 2.1% |
| Refugio County | 1,897 | 25.7% | 6.7% |
| Ward County | 1,894 | 17.8% | 11.4% |
| Bailey County | 1,892 | 26.4% | 17.0% |
| Mason County | 1,872 | 46.7% | 3.0% |
| Yoakum County | 1,870 | 23.7% | 51.7% |
| Starr County | 1,810 | 3.0% | 45.5% |
| Brewster County | 1,761 | 19.1% | 6.4% |
| Hartley County | 1,746 | 28.8% | 8.0% |
| Young County | 1,701 | 9.2% | 9.3% |
| Brooks County | 1,689 | 23.4% | 16.3% |
| Jones County | 1,568 | 7.8% | 8.3% |
| Falls County | 1,553 | 8.7% | 1.6% |
| Wilbarger County | 1,532 | 11.3% | 4.4% |
| Maverick County | 1,422 | 2.6% | 3.1% |
| Navarro County | 1,349 | 2.8% | 2.5% |
| Floyd County | 1,315 | 20.4% | 13.3% |
| Moore County | 1,311 | 6.0% | 4.6% |
| Schleicher County | 1,294 | 37.4% | 2.0% |
| Carson County | 1,286 | 20.8% | 3.7% |
| La Salle County | 1,279 | 18.6% | 3.0% |
| Wheeler County | 1,253 | 23.2% | 3.2% |
| Trinity County | 1,225 | 8.4% | 2.2% |
| Ochiltree County | 1,189 | 11.6% | 3.9% |
| Concho County | 1,184 | 29.0% | 2.0% |
| Glasscock County | 1,179 | 96.2% | 5.0% |
| Runnels County | 1,155 | 11.0% | 3.0% |
| Upton County | 1,137 | 33.9% | 4.1% |
| Mitchell County | 1,113 | 11.8% | 10.7% |
| Zavala County | 1,103 | 9.4% | 3.1% |
| Nolan County | 1,094 | 7.2% | 6.1% |
| Wichita County | 1,007 | 0.8% | 16.2% |
| Jeff Davis County | 961 | 41.0% | 14.0% |
| McCulloch County | 945 | 11.4% | 3.0% |
| Hansford County | 937 | 16.7% | 5.0% |
| Hemphill County | 932 | 24.5% | 3.0% |
| Hutchinson County | 923 | 4.2% | 3.4% |
| Irion County | 923 | 57.7% | 2.0% |
| Presidio County | 894 | 11.4% | 20.4% |
| Haskell County | 886 | 15.0% | 5.3% |
| Dallam County | 884 | 13.2% | 11.9% |
| Rains County | 862 | 7.9% | 1.0% |
| Crosby County | 859 | 14.2% | 15.5% |
| Franklin County | 840 | 7.9% | 2.0% |
| Hudspeth County | 822 | 23.6% | 13.0% |
| Donley County | 817 | 22.2% | 4.0% |
| Garza County | 804 | 12.5% | 12.0% |
| Coke County | 765 | 23.0% | 3.0% |
| Sutton County | 729 | 17.7% | 2.0% |
| Edwards County | 705 | 35.2% | 2.0% |
| Menard County | 702 | 31.3% | 2.0% |
| Sherman County | 689 | 22.7% | 4.0% |
| Lipscomb County | 665 | 20.1% | 3.0% |
| Kinney County | 626 | 17.4% | 2.0% |
| Armstrong County | 623 | 32.8% | 4.0% |
| Willacy County | 599 | 2.7% | 17.9% |
| Cochran County | 573 | 18.3% | 27.0% |
| Knox County | 557 | 15.0% | 3.7% |
| Dickens County | 541 | 22.1% | 3.0% |
| Baylor County | 517 | 13.9% | 6.0% |
| Briscoe County | 478 | 29.2% | – |
| Oldham County | 476 | 23.2% | – |
| Crockett County | 462 | 12.4% | – |
| Collingsworth County | 448 | 14.7% | – |
| Reagan County | 400 | 11.9% | – |
| Reeves County | 400 | 2.9% | – |
| Coleman County | 397 | 4.5% | – |
| Roberts County | 374 | 40.3% | – |
| Sterling County | 373 | 32.6% | – |
| Hardeman County | 358 | 8.7% | – |
| Borden County | 356 | 55.5% | – |
| Winkler County | 348 | 4.9% | – |
| Kent County | 326 | 40.3% | – |
| McMullen County | 318 | 44.9% | – |
| Archer County | 308 | 3.4% | – |
| Motley County | 297 | 24.5% | – |
| Kenedy County | 265 | 63.7% | – |
| Zapata County | 222 | 1.6% | – |
| Stonewall County | 221 | 14.8% | – |
| Stephens County | 214 | 2.2% | – |
| Terrell County | 213 | 21.7% | – |
| Crane County | 205 | 4.7% | – |
| Culberson County | 177 | 7.4% | – |
| Fisher County | 152 | 3.8% | – |
| Cottle County | 128 | 8.5% | – |
| Childress County | 105 | 1.5% | – |
| Foard County | 104 | 7.8% | – |
| Hall County | 100 | 3.0% | – |
| Rockwall County | 80 | 0.1% | – |
| Delta County | 76 | 1.4% | – |
| Loving County | 54 | 65.9% | – |
| Throckmorton County | 53 | 3.3% | – |
| Shackelford County | 35 | 1.0% | – |
| King County | 17 | 6.0% | – |
Counties with the highest modeled arsenic share: Dawson County (82.5%), Andrews County (72.1%), Gaines County (60.7%), Terry County (60.7%), Yoakum County (51.7%).
After you get results
Enter your numbers in the test results tool to see what needs treating and in what order. The guide to reading a well water test explains units and limits.
Common questions
Does Texas offer free well water testing?
Texas A&M AgriLife Extension's Texas Well Owner Network, funded through a Clean Water Act grant, holds local well-water screenings for total coliform, E. coli, nitrate-nitrogen and salinity at $15 per sample as of 2026.
Who oversees private wells in Texas?
Texas Groundwater Protection Committee (Private Wells) publishes guidance for private well owners. Private wells aren’t covered by the federal Safe Drinking Water Act, so testing and treatment are up to the owner.
How many people use private wells in Texas?
USGS estimates about 1,651,000 people, or 6.6% of the population in 2010. That ranks 7th of the states covered by the estimate.
What should I test my well for in Texas?
Test every year for total coliform bacteria and nitrate, plus pH, hardness, iron and manganese before buying equipment. Arsenic is a known concern in parts of Texas, so add it to the first test.
Sources
- Texas Groundwater Protection Committee: Private Wells
- Texas Groundwater Protection Committee: well water testing
- Texas certified laboratories
- Texas free or low-cost testing
- USGS data release: domestic well locations and populations served, 2000 and 2010 (Johnson, Belitz and Lombard, 2019)
- CDC Environmental Public Health Tracking: private well water data (from USGS)