Groundwater in Zavala County contains radon, iron, chloride, and several other contaminants that exceed EPA health standards, including manganese, nitrate, sulfate, and uranium. These levels are concerning enough that well owners should be aware of them.
The rock formations beneath this area naturally release these minerals and elements into the water. Radon seeps from uranium present in the rock. Iron and manganese dissolve from the rock as water moves through it. Chloride, sulfate, and sodium accumulate in the groundwater because of the local geology and, in some cases, past or present land use such as agriculture or oil and gas activity.
This county's groundwater is very hard, with elevated calcium, magnesium, sodium, and iron driving that character. The rock layers here naturally contain these minerals, which dissolve into water as it passes through the ground. These mineral characteristics are widespread across wells in the county.
Zavala County wells sometimes contain chloride, iron, manganese, nitrate, radon, sulfate, and uranium at levels above EPA health standards. Nitrate can interfere with oxygen in infants' blood. Uranium and radon are radioactive and can increase cancer risk. Manganese affects the developing brain. Iron and sulfate at high levels can cause stomach problems.
County wells are very hard, which means white scale builds up inside pipes and appliances. You may notice a metallic or bitter taste. Staining can appear on laundry and fixtures. The extreme hardness here shortens the lifespan of water heaters and dishwashers. High sodium in the water is also a concern for people watching their salt intake.
Because every well is different, your water may have much higher or lower levels than what is common across the county, and testing is the only way to know what is actually in your well so you can treat it properly. A comprehensive metals and minerals panel costs between $200 and $400 and would check all these concerns at once. Water softeners or iron filters may help depending on your results.
Not sure if your well is affected? Get certified results in 5–7 days.
Test Your Well Water with Tap Score →| Contaminant | Samples ⓘ | % Above MCL ⓘ | Distribution ⓘ | Confidence ⓘ | Risk ⓘ |
|---|---|---|---|---|---|
| Radon | 3 | 33% | Low | High ⓘ | |
| Iron | 258 | 32% | High | High | |
| Chloride | 8 | 25% | Low | High ⓘ | |
| Sulfate | 8 | 25% | Low | High ⓘ | |
| Manganese | 224 | 12% | High | Moderate | |
| Nitrate | 28 | 4% | Moderate |
Moderate
Elevated concentration, not % above limit
|
|
| Uranium | 61 | 2% | Moderate | Low | |
| Arsenic | 148 | 0% | High | Low | |
| Fluoride | 562 | 0% | High | Low | |
| HFPO-DA (GenX) ⓘ municipal | 8 | 0% | Low | Safe ⓘ | |
| Lead | 148 | 0% | High | Low | |
| Nitrite | 6 | 0% | Low | Safe ⓘ | |
| PFHxS ⓘ municipal | 8 | 0% | Low | Safe ⓘ | |
| PFNA ⓘ municipal | 8 | 0% | Low | Safe ⓘ | |
| PFOA ⓘ municipal | 8 | 0% | Low | Safe ⓘ | |
| PFOS ⓘ municipal | 8 | 0% | Low | Safe ⓘ | |
| PFBS ⓘ municipal | 8 | — | Low | Safe ⓘ | |
| Sodium | 8 | — | Low | Low ⓘ | |
| Hardness | 8 | — | Low | Low ⓘ | |
| pH | 8 | — | Low | Low ⓘ |
MCL = Maximum Contaminant Level (EPA limit for public water; used as benchmark for private wells). Distribution shows % of sampled wells in each concentration band. Methodology.
* Microbial contaminants (E. coli, coliform) reflect only samples from the last 10 years.
Data shows potential risk — a certified test confirms whether your water is affected.
Order a Tap Score Test →Population-level CDC data. Not individual risk prediction.
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