Texas has one of the largest populations of private well users in the country, spread across a huge range of geology — from Hill Country limestone to West Texas and Panhandle groundwater to East Texas sandy soils. Unlike a public water system, a private well is not regulated under the EPA’s Safe Drinking Water Act, and no state agency routinely tests it for you — testing, and paying for it, is entirely the well owner’s responsibility.
Why test
A well can look, taste, and smell completely normal while still carrying contaminants at levels that matter for health — bacteria, nitrate, and arsenic in particular have no reliable taste or odor warning sign. Groundwater conditions can also change over time (after drought, flooding, nearby land-use changes, or well aging), so a well that tested clean years ago isn’t guaranteed to still be clean today.
What to test for
A baseline panel for a Texas well should include:
- Total coliform bacteria and E. coli — indicates whether the well or wellhead may be vulnerable to contamination.
- Nitrate — a concern in agricultural areas and near livestock operations, and especially important if anyone in the household mixes infant formula with well water.
- Arsenic — naturally occurring arsenic has been documented in groundwater in parts of Texas, including areas of the Panhandle and West Texas; it has no taste or odor at concerning levels.
- Lead — relevant mainly for older plumbing rather than the water source itself, but worth including in a baseline panel.
Depending on your specific area, a lab or local extension office can advise on additional tests — for example, some Texas groundwater regions also warrant checking for naturally occurring radionuclides such as uranium or radium, particularly in parts of the state with granite or certain sedimentary aquifers.
How often to test
EPA guidance recommends testing private wells for bacteria and nitrate at least once a year, and re-testing any time water quality noticeably changes (taste, odor, color), after any well or plumbing work, or after nearby flooding.
Where to find a certified lab
The Texas Commission on Environmental Quality (TCEQ) publishes guidance for locating a laboratory accredited under the National Environmental Laboratory Accreditation Program (NELAP) for drinking-water testing — see the source link above for step-by-step instructions on searching the accreditation database by location and test type.
After you test
If a result comes back above a health-based guideline, see our filter guides for which treatment technologies are certified to address the specific contaminant found — testing first means you’re not guessing at (or paying for) treatment you may not need.