Groundwater in Pennington County contains iron, manganese, arsenic, lead, and sulfate at levels that exceed EPA health standards. These contaminants are present at concentrations serious enough that well owners need to test their water and consider treatment.
The rock layers beneath this county naturally contain iron and manganese minerals that dissolve into groundwater over time. Arsenic occurs naturally in these same rock formations and releases into water under certain chemical conditions in the soil. Sulfate and lead can come from both natural sources in the rock and from human activities on the land above.
Groundwater in this county is very hard, driven by elevated calcium and magnesium from the rock formations below, and it also contains high levels of iron. The Lower Cretaceous rock layers here are rich in minerals that break down slowly and release into the water as it filters through. These characteristics are widespread across wells throughout the county.
Wells in Pennington County commonly exceed EPA health standards for arsenic, lead, manganese, iron, and sulfate. Arsenic and lead are toxic metals that build up in your body over time and can damage your kidneys, nervous system, and bones. Manganese affects brain development in children and can cause nerve problems in adults. Iron and sulfate at high levels also pose health concerns when consumed regularly.
The very hard water in this county's wells causes stubborn staining on fixtures and dishes that is hard to remove. Scale builds up inside pipes and water heaters, shortening the lifespan of appliances like dishwashers and water heaters. You may notice a metallic taste or rotten egg smell from the iron and sulfate levels.
We recommend getting your well tested right away with a comprehensive metals and minerals panel, which typically costs between $200 and $400. Every well is different, and your water could have higher or lower levels than what is common here. Testing is the only way to know exactly what is in your well so you can treat it properly. Iron and manganese can be removed with oxidation filters or water softeners, while arsenic and lead require specialized treatment 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 ⓘ |
|---|---|---|---|---|---|
| Iron | 17 | 71% | Moderate | High | |
| Manganese | 16 | 50% | Moderate | High | |
| Arsenic | 15 | 33% | Moderate | High | |
| Lead | 7 | 14% | Low | Moderate ⓘ | |
| Sulfate | 39 | 5% | Moderate | Moderate | |
| PFHxS ⓘ municipal | 4 | 0% | Low | Safe ⓘ | |
| PFOA ⓘ municipal | 4 | 0% | Low | Safe ⓘ | |
| PFNA ⓘ municipal | 4 | 0% | Low | Safe ⓘ | |
| PFOS ⓘ municipal | 4 | 0% | Low | Safe ⓘ | |
| HFPO-DA (GenX) ⓘ municipal | 4 | 0% | Low | Safe ⓘ | |
| Chloride | 50 | 0% | Moderate | Low | |
| Fluoride | 16 | 0% | Moderate | Low | |
| Nitrate | 44 | 0% | Moderate | Low | |
| Sodium | 18 | — | — | Moderate | Low |
| pH | 11 | — | — | Low | Low |
| Fecal Coliform | 1 | 0% | Low | Safe ⓘ | |
| Hardness | 10 | — | — | Low | Low |
| E. coli | 1 | 0% | Low | Safe ⓘ | |
| Nitrite | 1 | 0% | Low | Safe ⓘ | |
| PFBS ⓘ municipal | 4 | — | Low | 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.
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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