Well owners in Starr County need to know that arsenic, nitrate, uranium, fluoride, and manganese are present in the groundwater here. Several of these contaminants exceed EPA health standards, which means they show up at levels that warrant attention.
These contaminants come from natural sources in the rock beneath the county. Arsenic, uranium, and manganese occur naturally in the aquifer rock, while nitrate enters from agricultural and septic sources above ground. The coastal uplands aquifer system here allows water to move through rock layers that release these elements into the groundwater.
Groundwater in Starr County shows moderate iron content, which is the main aesthetic characteristic of the water. Iron comes from the natural rock and soil minerals in this region, and it concentrates as water passes through the aquifer. Elevated iron is common across many wells in the county.
Wells in Starr County commonly contain arsenic, fluoride, uranium, nitrate, and manganese at levels above EPA health standards. Arsenic and uranium are radioactive elements that can damage your kidneys and bones with long-term exposure. Nitrate is especially dangerous for babies and can prevent their blood from carrying oxygen. Fluoride and manganese at elevated levels can affect bone and brain development, particularly in children.
Iron and manganese in county wells create visible and annoying problems in your home. Iron stains fixtures, laundry, and dishes orange or brown. Manganese leaves black stains and can create a metallic taste in your water. These minerals also build up as scale inside pipes and water heaters, shortening how long appliances last.
We recommend testing your well with a comprehensive panel since multiple contaminants exceed health standards in this county. 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 water so you can treat it properly. A comprehensive metals and minerals panel costs between $200 and $400 and can guide you toward solutions like reverse osmosis, distillation, or ion exchange systems.
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 ⓘ |
|---|---|---|---|---|---|
| Arsenic | 89 | 44% | Moderate | High | |
| Nitrate | 25 | 24% | Moderate | High | |
| Iron | 90 | 11% | Moderate | Moderate | |
| Manganese | 90 | 7% | Moderate | Moderate | |
| Uranium | 19 | 5% | Moderate | Moderate | |
| Fluoride | 120 | 2% | High | Low | |
| HFPO-DA (GenX) ⓘ municipal | 23 | 0% | Moderate | Safe | |
| Lead | 90 | 0% | Moderate | Low | |
| PFHxS ⓘ municipal | 23 | 0% | Moderate | Safe | |
| PFNA ⓘ municipal | 23 | 0% | Moderate | Safe | |
| PFOA ⓘ municipal | 23 | 0% | Moderate | Safe | |
| PFOS ⓘ municipal | 23 | 0% | Moderate | Safe | |
| PFBS ⓘ municipal | 23 | — | Moderate | 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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