Groundwater in Frio County contains iron, manganese, chloride, fluoride, nitrate, and sulfate. Several of these contaminants exceed EPA health standards, making testing and awareness important for well owners.
The rock beneath this area naturally contains minerals that dissolve into water as it moves underground. Iron and manganese come from the rock itself, while chloride and sulfate accumulate in the groundwater over time. Nitrate can enter from agricultural land use and septic systems in the area.
Groundwater in this county is very hard, driven by elevated calcium and magnesium combined with moderate sodium and sulfate levels. The underlying geology releases these minerals into the water as it flows through the rock layers below. These characteristics are widespread across wells throughout the county.
Wells in Frio County commonly contain chloride, fluoride, iron, manganese, nitrate, and sulfate at levels that exceed EPA health standards. Chloride and sulfate can affect kidney function and digestive health with long-term exposure. Nitrate is particularly concerning for infants and can interfere with oxygen transport in the blood. Fluoride, iron, and manganese can cause bone and dental issues, nervous system problems, and organ damage when consumed at elevated levels over time.
The very hard water in county wells leaves white scale buildup inside pipes and appliances, reducing water flow and shortening the lifespan of water heaters and dishwashers. Iron creates rust-colored stains on laundry, dishes, and plumbing fixtures. You may notice a metallic or musty taste and odor in your water. The mineral content also makes soap less effective for cleaning.
Your well may have higher or lower levels than what is common across the county, so we recommend testing to find out what is actually in your water. A comprehensive metals and minerals panel costs between $200 and $400 and will show exactly what needs treatment. Once you know what you are dealing with, a water softener or iron filter can address the main concerns. Testing is the only way to make informed decisions about your family's water.
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 ⓘ |
|---|---|---|---|---|---|
| Iron | 326 | 56% | High | High | |
| Manganese | 223 | 20% | High | High | |
| Chloride | 73 | 19% | Moderate | High | |
| Sulfate | 71 | 17% | Moderate | High | |
| Nitrate | 109 | 5% | High |
Moderate
Elevated concentration, not % above limit
|
|
| Fluoride | 511 | 0% | High | Low | |
| Arsenic | 170 | 0% | High | Low | |
| HFPO-DA (GenX) ⓘ municipal | 12 | 0% | Low | Safe | |
| Lead | 170 | 0% | High | Low | |
| Nitrite | 2 | 0% | Low | Safe ⓘ | |
| PFHxS ⓘ municipal | 12 | 0% | Low | Safe | |
| PFNA ⓘ municipal | 12 | 0% | Low | Safe | |
| PFOA ⓘ municipal | 12 | 0% | Low | Safe | |
| PFOS ⓘ municipal | 12 | 0% | Low | Safe | |
| Radon | 2 | 0% | Low | Low ⓘ | |
| Uranium | 51 | 0% | Moderate | Low | |
| Hardness | 70 | — | Moderate | Low | |
| PFBS ⓘ municipal | 12 | — | Low | Safe | |
| pH | 57 | — | Moderate | Low | |
| Sodium | 70 | — | Moderate | 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.
Loading recent water news…