Groundwater in McLennan County contains radon, iron, arsenic, fluoride, and manganese at levels that exceed EPA health standards. These contaminants are present at concerning concentrations and warrant testing and treatment consideration for private wells.
These contaminants come from the rock layers beneath the county. Radon seeps naturally from uranium in the rock, while iron, manganese, and arsenic dissolve into water as it moves through the underground geology. Nitrate typically enters from farm and septic system sources in the area.
Groundwater in this county is not hard, but it carries very high sodium and high sulfate from the rocks below. As water sits in contact with these mineral-rich layers, sodium and sulfate dissolve into the water supply. These characteristics are common across many wells throughout McLennan County.
Wells in McLennan County commonly have arsenic, fluoride, iron, manganese, nitrate, and radon at levels above EPA health standards. Arsenic and radon can increase cancer risk with long-term exposure. Fluoride at elevated levels can cause bone and dental problems. Nitrate is especially dangerous for babies and can make it hard for blood to carry oxygen. Manganese and iron at high levels can affect the nervous system and cause other health issues over time.
The very high sodium in county well water can affect how your water tastes and may be a concern if you have high blood pressure or heart disease. While the water is soft, the iron can cause orange or brown staining on sinks, toilets, and laundry. You might also notice a metallic or bitter taste, or a rotten egg smell from sulfate and other minerals. These stains are hard to remove and can build up over time.
We recommend testing your well with a comprehensive panel to see what is actually in your water, since every well is different and yours could have higher or lower levels than the county average. A full metals and minerals panel runs between $200 and $400. Testing is the only way to know what treatment your well needs, whether that is a water softener, a special filter, or another system. Start with testing so you can make the best choice for your family.
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 | 2 | 50% | Low | High ⓘ | |
| Iron | 529 | 13% | High | Moderate | |
| Arsenic | 162 | 12% | High | Moderate | |
| Nitrate | 40 | 2% | Moderate | Low | |
| Fluoride | 680 | 1% | High | Low | |
| Manganese | 387 | 1% | High | Low | |
| Chloride | 2 | 0% | Low | Low ⓘ | |
| HFPO-DA (GenX) ⓘ municipal | 108 | 0% | High | Safe | |
| Lead | 156 | 0% | High | Low | |
| Nitrite | 2 | 0% | Low | Safe ⓘ | |
| PFHxS ⓘ municipal | 108 | 0% | High | Low | |
| PFNA ⓘ municipal | 108 | 0% | High | Safe | |
| PFOA ⓘ municipal | 108 | 0% | High | Safe | |
| PFOS ⓘ municipal | 108 | 0% | High | Safe | |
| Sulfate | 2 | 0% | Low | Low ⓘ | |
| Uranium | 42 | 0% | Moderate | Low | |
| Total Coliform | 2* | 0% | Low | Safe ⓘ | |
| Sodium | 2 | — | Low | Low ⓘ | |
| pH | 2 | — | Low | Low ⓘ | |
| PFBS ⓘ municipal | 108 | — | High | Low | |
| Hardness | 2 | — | Low | Low ⓘ | |
| E. coli | 2* | 0% | Low | Safe ⓘ |
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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