Groundwater in Door County contains arsenic, manganese, and PFHXS, along with several other contaminants including chloride, fluoride, iron, lead, and PFOS. Multiple contaminants exceed EPA health standards, making testing and treatment important for well owners.
These contaminants come from the rock layers beneath the county. Arsenic, manganese, and iron dissolve naturally from the limestone and other stone as groundwater sits in contact with it over time. Chloride and fluoride enter from both natural sources in the rock and from human activities like road salt and land use.
Groundwater in this county is very hard, driven by elevated calcium and magnesium from the limestone below. As water moves slowly through these mineral-rich rock layers, it picks up hardness minerals naturally. Very hard water is extremely common across wells in Door County.
Wells in Door County commonly exceed EPA health standards for arsenic, fluoride, lead, and PFOA and PFHXS chemicals. Arsenic builds up in your body over time and raises cancer risk. Lead harms children's brain development and nervous systems. Fluoride at elevated levels can damage tooth enamel. PFOA and PFHXS are synthetic chemicals linked to serious health effects including liver damage and immune system harm.
The mineral content in county wells creates noticeable quality-of-life problems. Moderate iron causes orange-brown staining on sinks and laundry. The very hard water leaves white crusty scale on pipes and fixtures that can shorten the lifespan of water heaters and dishwashers. Scale also builds up inside pipes and reduces water flow.
We recommend testing your well to know exactly what you are dealing with. Every well is different--yours may have 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 it can be properly treated. Because multiple health concerns are present, we recommend a comprehensive metals and minerals panel, which typically costs $200-400. Treatment options may include activated carbon filters for chemicals and water softeners or iron filters for minerals.
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 ⓘ |
|---|---|---|---|---|---|
| Arsenic | 17 | 65% | Moderate | High | |
| Manganese | 65 | 37% | Moderate | High | |
| PFHxS ⓘ municipal | 14 | 36% | Low | High | |
| Sulfate | 48 | 29% | Moderate | High | |
| Iron | 66 | 29% | Moderate | High | |
| PFOS ⓘ municipal | 14 | 14% | Low | Moderate | |
| Lead | 18 | 11% | Moderate | Moderate | |
| Chloride | 61 | 10% | Moderate | Moderate | |
| Fluoride | 41 | 2% | Moderate | Low | |
| PFOA ⓘ municipal | 14 | 0% | Low | Low | |
| PFNA ⓘ municipal | 14 | 0% | Low | Safe | |
| Nitrite | 13 | 0% | Low | Low | |
| Nitrate | 43 | 0% | Moderate | Low | |
| HFPO-DA (GenX) ⓘ municipal | 14 | 0% | Low | Safe | |
| Hardness | 47 | — | Moderate | Low | |
| pH | 66 | — | Moderate | Low | |
| Sodium | 37 | — | Moderate | Low | |
| PFBS ⓘ municipal | 14 | — | 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.
* 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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