Groundwater in Karnes County contains chloride, arsenic, and manganese that well owners should monitor. Several contaminants exceed EPA health standards, including arsenic, chloride, fluoride, iron, manganese, and nitrate, making testing and treatment important steps for private well owners here.
These contaminants come from two sources. Chloride and sodium enter the groundwater naturally from old saltwater that remains trapped in the rock layers beneath this area. Arsenic, manganese, and iron come from the rock itself as groundwater slowly dissolves minerals over time. Nitrate can also seep down from surface activities like agriculture or septic systems.
Groundwater in Karnes County is very hard, driven by elevated calcium and magnesium minerals that dissolve from the rock as water moves underground. Sodium levels are very high, adding to the mineral load in most wells here. These mineral-rich conditions are common across the county because of the rock composition and the slow movement of ancient saltwater through the aquifer system.
Wells in Karnes County commonly contain arsenic, chloride, fluoride, iron, manganese, and nitrate at levels above EPA health standards. Arsenic can damage your kidneys and increase cancer risk with long-term exposure. Nitrate is especially dangerous for infants and can cause a serious blood condition. Manganese can harm your nervous system and brain development in children. Fluoride at high levels can weaken tooth enamel and damage bones over time.
The water in this county is extremely hard, which causes scale buildup in pipes and appliances and shortens the lifespan of water heaters and dishwashers. You may notice rust stains on sinks and laundry, difficulty getting soap to lather, and a salty taste to your drinking water. White crusty deposits can form inside kettles and on fixtures.
We recommend a comprehensive water test right away since multiple contaminants exceed health standards in this county. Every well is different, and your well may 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 will tell you exactly what you are dealing with. Depending on your results, treatment options include arsenic filters, water softeners, and reverse osmosis 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 ⓘ |
|---|---|---|---|---|---|
| Chloride | 14 | 57% | Low | High | |
| Arsenic | 59 | 46% | Moderate | High | |
| Manganese | 77 | 10% | Moderate | Moderate | |
| Iron | 114 | 9% | High | Moderate | |
| Nitrate | 19 | 5% | Moderate | Moderate | |
| Fluoride | 228 | 2% | High | Low | |
| HFPO-DA (GenX) ⓘ municipal | 7 | 0% | Low | Safe ⓘ | |
| Lead | 59 | 0% | Moderate | Low | |
| Nitrite | 8 | 0% | Low | Safe ⓘ | |
| PFHxS ⓘ municipal | 7 | 0% | Low | Safe ⓘ | |
| PFNA ⓘ municipal | 7 | 0% | Low | Safe ⓘ | |
| PFOA ⓘ municipal | 7 | 0% | Low | Safe ⓘ | |
| PFOS ⓘ municipal | 7 | 0% | Low | Safe ⓘ | |
| Radon | 1 | 0% | Low | Low ⓘ | |
| Sulfate | 14 | 0% | Low | Low | |
| Uranium | 22 | 0% | Moderate | Low | |
| Sodium | 14 | — | Low | Low | |
| pH | 14 | — | Low | Low | |
| PFBS ⓘ municipal | 7 | — | Low | Safe ⓘ | |
| Hardness | 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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