Groundwater in Karnes County contains chloride, arsenic, and manganese that well owners should be aware of. Multiple contaminants exceed EPA health standards, including arsenic, chloride, fluoride, iron, manganese, and nitrate, making testing and treatment important for your household water.
The rock layers beneath Karnes County naturally release these contaminants as water moves slowly underground. Chloride and other salts dissolve from deeper sedimentary layers and can rise toward the surface in this coastal uplands area. Arsenic, iron, and manganese all occur naturally in the rock, and human activity like oil and gas operations can push saltwater upward, adding to the chloride burden. Nitrate enters from fertilizers and septic systems on the land above.
Groundwater in this county is very hard and notably high in sodium, driven by calcium, magnesium, and dissolved salts from the surrounding rock. The coastal uplands geology naturally concentrates these minerals as water passes through sedimentary layers rich in salt and mineral content. Hard water and elevated sodium are widespread across wells throughout Karnes County.
Arsenic, chloride, fluoride, iron, manganese, and nitrate are found at levels exceeding EPA health standards in wells across Karnes County. Arsenic can damage your kidneys and increase cancer risk with long-term exposure. Fluoride at elevated levels can harm developing teeth and bones. Nitrate is especially dangerous for infants and young children, affecting how their bodies use oxygen. Manganese can affect your nervous system development over time.
The water in this county is very hard, which means you will see white crusty buildup on faucets and fixtures. Hard water can shorten the lifespan of water heaters, dishwashers, and other appliances. The high sodium content means the water may taste salty. You may also notice a metallic taste or smell from the iron and manganese in the water.
Your well is unique, and your water could have higher or lower levels than what is common across the county. Testing is the only way to know what is actually in your well so you can treat it properly. Since multiple analytes exceed health standards here, a comprehensive metals and minerals panel is recommended, which typically costs $200-400. Treatment options like reverse osmosis systems or specialized filtration can address these concerns.
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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