Groundwater in Dane County contains lead, arsenic, and chloride. Arsenic and lead exceed EPA health standards and warrant attention.
Lead and arsenic enter groundwater from natural rock layers that wells draw from. Chloride comes from road salt applied to highways and surfaces that seeps downward. The limestone and sandstone rock here naturally contains small amounts of these elements that dissolve as water passes through.
Groundwater in this county is moderately hard, driven by calcium and magnesium from the limestone bedrock. As water moves slowly through these rock layers, it picks up dissolved minerals that create the hardness. Moderate hardness is common across wells throughout the county.
Arsenic and lead are found in wells across Dane County at levels that exceed EPA health standards. Arsenic can harm your skin, nerves, and organs over time. Lead damages the brain and nervous system, especially in children, and can affect the kidneys and heart at any age.
The mineral content in county wells is generally low, so most well owners do not experience staining, scale, or taste problems from hard water. Wells in this county tend to have balanced water quality on the mineral side, which means fewer issues with appliances and plumbing.
We recommend testing your well for both arsenic and lead using a comprehensive metals and minerals panel, which typically costs between two hundred and four hundred dollars. Every well is different, and your well may contain higher or lower levels than what is common in the county. Testing is the only way to know what is actually in your water so you can install the right treatment, such as arsenic and lead removal filters.
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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