Groundwater in Pennington County contains iron, arsenic, manganese, lead, and nitrate. Several of these contaminants exceed EPA health standards, making them a concern for well owners in this area.
These contaminants come from the rock itself beneath the county. The Lower Cretaceous rocks here naturally release iron and manganese as water passes through them over time. Arsenic and lead also occur naturally in these rock layers. Nitrate can enter groundwater from agricultural practices and septic systems in the area.
Groundwater in Pennington County is very hard, driven by elevated calcium and magnesium from the rock below, and it carries notable amounts of iron and sodium. The Lower Cretaceous rock formation dissolves minerals into the water as it flows through. These characteristics are widespread across wells throughout the county.
Wells in Pennington County commonly exceed EPA health standards for arsenic, lead, nitrate, iron, and manganese. Arsenic damages your kidneys and increases cancer risk over time. Lead harms children's brain development and learning ability, even at low levels. Nitrate is especially dangerous for infants and can interfere with oxygen in the blood. Manganese affects your nervous system and can harm brain function with long-term exposure.
The very hard water in county wells causes visible staining from iron and manganese. You will see rust-colored or brown stains on fixtures, laundry, and dishes. Scale buildup clogs pipes and reduces water pressure. The water may taste salty or metallic. Very hard water also shortens the lifespan of water heaters and dishwashers.
We recommend a comprehensive metals and minerals panel right away--testing is the only way to know what is actually in your well since every well is different. Your water could have higher or lower levels than what is common here. A comprehensive panel typically costs between two hundred and four hundred dollars. Treatment options include reverse osmosis systems, whole-house filters, and water softeners depending on your specific results.
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 | 19 | 79% | Moderate | High | |
| Arsenic | 7 | 57% | Low | High ⓘ | |
| Manganese | 19 | 47% | Moderate | High | |
| Lead | 14 | 7% | Low | Moderate | |
| Nitrate | 15 | 7% | Moderate | Moderate | |
| Chloride | 49 | 0% | Moderate | Low | |
| Fluoride | 19 | 0% | Moderate | Low | |
| HFPO-DA (GenX) ⓘ municipal | 4 | 0% | Low | Safe ⓘ | |
| Nitrite | 5 | 0% | Low | Low ⓘ | |
| PFHxS ⓘ municipal | 4 | 0% | Low | Safe ⓘ | |
| PFNA ⓘ municipal | 4 | 0% | Low | Safe ⓘ | |
| PFOA ⓘ municipal | 4 | 0% | Low | Safe ⓘ | |
| PFOS ⓘ municipal | 4 | 0% | Low | Safe ⓘ | |
| Sulfate | 25 | 0% | Moderate | Low | |
| Sodium | 19 | — | Moderate | Low | |
| pH | 14 | — | Low | Low | |
| PFBS ⓘ municipal | 4 | — | 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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