Groundwater in Bexar County contains arsenic, chloride, fluoride, iron, lead, manganese, nitrate, radon, and sulfate at levels that exceed EPA health standards. These contaminants are present at concentrations serious enough that well owners should test their water and consider treatment options.
These contaminants come from a mix of sources tied to the local rock and human activity. The underground rocks in this area naturally contain minerals and elements like arsenic and radon. Human activities such as farming, urban development, and septic systems add chloride, nitrate, and other salts to the groundwater. Lead and manganese can leach from pipes and soil as water moves through the ground.
Groundwater in this county is very hard, driven by elevated calcium and magnesium dissolved from the rock below. The local geology naturally produces this mineral-rich water as it flows through limestone and other rock layers. Very hard water is the norm across most wells in Bexar County.
Wells in Bexar County can have arsenic, chloride, fluoride, iron, lead, manganese, nitrate, radon, and sulfate at levels above EPA health standards. Arsenic and radon are serious concerns because they can increase cancer risk over time. Lead harms children's brain development and learning. Nitrate is dangerous for babies and can cause serious health problems. Manganese can affect the nervous system, and fluoride at high levels can damage teeth and bones.
The very hard water in county wells causes scale buildup on pipes and fixtures, leaving white chalky deposits. This extreme hardness can shorten the lifespan of water heaters, dishwashers, and other appliances. Hard water also makes it harder for soap to work and can leave your skin and hair feeling dry.
We recommend getting your well tested with a comprehensive panel since several contaminants exceed health standards in this county. Your well could have higher or lower levels than what is common here, and testing is the only way to know what is actually in your water so you can treat it properly. A comprehensive metals and minerals panel typically costs between two hundred and four hundred dollars. Treatment options include reverse osmosis systems for multiple contaminants or water softeners for hardness.
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 ⓘ |
|---|---|---|---|---|---|
| Sulfate | 3487 | 28% | High | High | |
| Chloride | 3582 | 27% | High | High | |
| Iron | 3269 | 6% | High | Moderate | |
| Radon | 39 | 5% | Moderate | Moderate ⓘ | |
| Manganese | 3090 | 3% | High | Low | |
| Fluoride | 5791 | 2% | High | Low | |
| Nitrate | 1575 | 1% | High | Low | |
| Lead | 2132 | 0% | High | Low | |
| Arsenic | 2601 | 0% | High | Low | |
| HFPO-DA (GenX) ⓘ municipal | 225 | 0% | High | Safe | |
| Nitrite | 1116 | 0% | High | Low | |
| PFHxS ⓘ municipal | 225 | 0% | High | Safe | |
| PFNA ⓘ municipal | 225 | 0% | High | Safe | |
| PFOA ⓘ municipal | 225 | 0% | High | Safe | |
| PFOS ⓘ municipal | 225 | 0% | High | Low | |
| Uranium | 685 | 0% | High | Low | |
| Hardness | 3428 | — | High | Low | |
| E. coli | 40* | 0% | Moderate | Low | |
| Total Coliform | 37* | 0% | Moderate | Low | |
| Sodium | 2462 | — | High | Low | |
| pH | 3587 | — | High | Low | |
| PFBS ⓘ municipal | 225 | — | High | 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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