Groundwater in McMullen County contains chloride, sulfate, iron, arsenic, manganese, nitrate, and uranium. Multiple contaminants exceed EPA health standards, making testing and treatment important for your well.
The Texas coastal uplands rock here naturally holds salt minerals like chloride and sulfate. Human activities including oil and gas operations, farming, and waste disposal add arsenic, nitrate, and other metals to the water as it moves through the ground.
Groundwater in this county is notably high in sodium, with moderate sulfate and iron present. These salt minerals dissolve naturally from the surrounding rock and concentrate as water sits underground. Most wells in McMullen County show these same characteristics.
McMullen County wells show elevated levels of arsenic, uranium, nitrate, and manganese that exceed EPA health standards. Arsenic and uranium are particularly concerning because they can damage kidneys and increase cancer risk with long-term exposure. Nitrate poses a specific threat to infants and can interfere with oxygen in the blood. Manganese affects the nervous system, especially in children.
The water in this county contains very high sodium, which gives it a salty or brackish taste that many people find unpleasant. High sulfate levels can create a rotten egg smell. Though the water is soft, the elevated iron can stain laundry, dishes, and fixtures with orange or brown marks.
We recommend you test your well water with a comprehensive metals and minerals panel since multiple contaminants exceed health standards. Your well may have higher or lower levels than what is common across the county, so testing is the only way to know what's actually in your water and how to treat it properly. A comprehensive panel typically costs $200-400. Treatment options like reverse osmosis systems or specific metal-removal filters can address multiple contaminants.
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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