Groundwater in Dane County contains iron, manganese, arsenic, chloride, lead, and nitrate. Several of these contaminants exceed EPA health standards and warrant attention from well owners.
The deep rock layers beneath Dane County naturally release iron, manganese, and arsenic as groundwater moves slowly through them over time. Nitrate enters from the surface through soil and is linked to agricultural activity and septic systems. Chloride and lead come from a mix of natural dissolution and human sources like road salt and corroded pipes.
Groundwater in Dane County is very hard, driven by elevated calcium and magnesium that dissolve from the limestone and rock below. As water sits in contact with these deep rock layers, it picks up these minerals over many years. Very hard water is the common condition across wells in this county.
Wells in Dane County commonly contain arsenic, chloride, iron, lead, manganese, and nitrate at levels exceeding EPA health standards. Arsenic can damage your kidneys and nervous system over time. Lead is especially harmful to children and can affect brain development and learning. Nitrate is dangerous for infants and can interfere with how blood carries oxygen. Manganese can harm your nervous system with long-term exposure. Iron and chloride also pose health concerns at elevated levels.
County wells are very hard, which means scale buildup will form inside pipes, water heaters, and dishwashers and can shorten their lifespan. The moderate iron levels in some wells cause rust-colored stains on clothes, sinks, and fixtures. You may notice a metallic taste or smell in your water. Hard water makes soap less effective for cleaning and can leave your skin feeling dry.
We recommend testing your well because multiple contaminants exceed health standards in this county. Every well is different, and your water may have higher or lower levels than what is common here. Testing is the only way to know what is actually in your well so it can be properly treated. A comprehensive metals and minerals panel typically costs between $200 and $400. Treatment options like iron removal systems, water softeners, and point-of-use filters 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 ⓘ |
|---|---|---|---|---|---|
| Iron | 271 | 25% | High | High | |
| Manganese | 260 | 20% | High | High | |
| Arsenic | 25 | 16% | Moderate | High | |
| Lead | 38 | 5% | Moderate | Moderate | |
| Nitrate | 189 | 3% | High | Low | |
| Chloride | 312 | 1% | High | Low | |
| Uranium | 3 | 0% | Low | Low ⓘ | |
| Sulfate | 239 | 0% | High | Low | |
| PFOS ⓘ municipal | 159 | 0% | High | Low | |
| PFOA ⓘ municipal | 159 | 0% | High | Low | |
| PFNA ⓘ municipal | 159 | 0% | High | Safe | |
| PFHxS ⓘ municipal | 159 | 0% | High | Low | |
| Nitrite | 133 | 0% | High | Low | |
| HFPO-DA (GenX) ⓘ municipal | 159 | 0% | High | Safe | |
| Fluoride | 217 | 0% | High | Low | |
| Sodium | 197 | — | High | Low | |
| pH | 310 | — | High | Low | |
| PFBS ⓘ municipal | 159 | — | High | Low | |
| Hardness | 298 | — | High | 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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