Groundwater in Presidio County contains radon, sulfate, arsenic, chloride, fluoride, iron, and manganese that well owners should know about. Several of these contaminants exceed EPA health standards and warrant attention.
These contaminants come from the rock layers beneath the county. Radon occurs naturally in certain rocks and seeps into groundwater over time. Arsenic, sulfate, and other minerals dissolve from the surrounding rock as water moves slowly through it. The arid landscape and limited rainfall mean water sits underground longer, giving it more time to pick up these dissolved substances.
Groundwater in this county is moderately hard and notably high in sodium and sulfate, with the sodium and sulfate coming from minerals in the underlying rock. As water percolates through the ground, it dissolves these natural minerals slowly and steadily. These characteristics show up across many wells in the county.
Wells in Presidio County contain several contaminants that exceed EPA health standards. Arsenic, fluoride, and radon are health concerns found in county well water. Arsenic and radon increase the risk of cancer over time. Fluoride at high levels can damage bones and teeth, especially in children.
County wells also contain elevated sodium, sulfate, and moderate hardness that affect daily life. High sodium can give water a salty taste and is a concern for people watching their salt intake. Sulfate and moderate hardness can leave spots on dishes and fixtures and create buildup in pipes and appliances. The moderately hard water in this county can shorten the lifespan of water heaters and dishwashers.
We recommend testing your well as soon as possible since every well is different and yours could have higher or lower levels than what is common here. Testing is the only way to know what is actually in your well so you can treat it properly. A comprehensive panel that checks for metals, minerals, and bacteria costs between $200 and $400. Treatment options like reverse osmosis or specialized filters can address multiple contaminants at once.
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 | 1 | 100% | Low | High ⓘ | |
| Sulfate | 15 | 33% | Moderate | High | |
| Arsenic | 144 | 23% | High | High | |
| Chloride | 15 | 13% | Moderate | Moderate | |
| Fluoride | 272 | 12% | High | Moderate | |
| Iron | 196 | 6% | High | Moderate | |
| Manganese | 181 | 5% | High |
Moderate
Elevated concentration, not % above limit
|
|
| HFPO-DA (GenX) ⓘ municipal | 2 | 0% | Low | Safe ⓘ | |
| Lead | 144 | 0% | High | Low | |
| Nitrate | 32 | 0% | Moderate | Low | |
| Nitrite | 1 | 0% | Low | Safe ⓘ | |
| PFHxS ⓘ municipal | 2 | 0% | Low | Safe ⓘ | |
| PFNA ⓘ municipal | 2 | 0% | Low | Safe ⓘ | |
| PFOA ⓘ municipal | 2 | 0% | Low | Safe ⓘ | |
| PFOS ⓘ municipal | 2 | 0% | Low | Safe ⓘ | |
| Uranium | 18 | 0% | Moderate | Low | |
| Hardness | 15 | — | Moderate | Low | |
| PFBS ⓘ municipal | 2 | — | Low | Safe ⓘ | |
| pH | 15 | — | Moderate | Low | |
| Sodium | 14 | — | 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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