Groundwater in McMullen County contains arsenic, chloride, iron, manganese, nitrate, sulfate, and uranium, several of which exceed EPA health standards. These contaminants are present at concerning levels that well owners should monitor and address.
The source of these contaminants comes from the natural rock and soil layers beneath the county. Saltwater and minerals naturally present in the coastal uplands rock dissolve into groundwater as it moves through the earth, while nitrate and uranium can seep in from land activities and natural deposits in the rock itself.
Groundwater in McMullen County is not hard, but it is high in sodium and sulfate. The coastal uplands rock in this area naturally releases these minerals into the water as it flows underground. These characteristics are widespread across wells throughout the county.
Wells in McMullen County show concerning levels of arsenic, uranium, nitrate, and manganese--all known to cause serious health problems with long-term exposure. Arsenic and uranium damage organs and increase cancer risk. Nitrate is especially dangerous for infants and can interfere with how blood carries oxygen. Manganese at elevated levels harms the nervous system and brain development in children.
The county's very high sodium content affects how water tastes and feels, and it can be a problem for people watching their salt intake. Iron and sulfate create staining on fixtures and laundry, and sulfate can give water a bitter taste and laxative effect. The good news is that the water here is not hard, so you won't see scale buildup in pipes and appliances the way people in other areas do.
Testing is the only way to know what is actually in your well, since every well is different and yours could have higher or lower levels than the county average. We recommend a comprehensive water panel that checks for metals, minerals, bacteria, and nitrate--this typically costs between two hundred and four hundred dollars. Treatment options like reverse osmosis, activated carbon filters, or ion exchange systems can address multiple concerns depending on what testing reveals.
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 ⓘ |
|---|---|---|---|---|---|
| Chloride | 111 | 40% | High | High | |
| Sulfate | 110 | 29% | High | High | |
| Iron | 116 | 25% | High | High | |
| Uranium | 10 | 20% | Low | High | |
| Arsenic | 52 | 19% | Moderate | High | |
| Manganese | 66 | 17% | Moderate | High | |
| Nitrate | 114 | 5% | High | Moderate | |
| Fluoride | 219 | 0% | High | Low | |
| Lead | 52 | 0% | Moderate | Low | |
| Nitrite | 2 | 0% | Low | Safe ⓘ | |
| Radon | 1 | 0% | Low | Low ⓘ | |
| Sodium | 111 | — | High | Low | |
| pH | 110 | — | High | Low | |
| Hardness | 111 | — | 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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