Groundwater in Door County contains arsenic, lead, and PFOS compounds that well owners should be aware of. Several of these contaminants exceed EPA health standards and warrant testing and treatment.
These contaminants come from the bedrock itself. Arsenic and lead dissolve naturally from the limestone and other stone layers beneath the county. PFOS is a synthetic chemical that enters some wells from industrial sources or past disposal practices in the area.
Groundwater in Door County is very hard, driven by calcium and magnesium from the limestone bedrock below. As water moves slowly through cracks in this rock, it picks up these minerals over time. Very hard water is common across wells throughout the county.
Wells in Door County commonly exceed EPA health standards for arsenic, lead, and forever chemicals called PFOS and PFHXS. Arsenic can build up in your body over years and raise cancer risk. Lead damages children's brains and nervous systems. PFOS and PFHXS are synthetic chemicals that can affect your immune system and other organs. These contaminants come from the rock, soil, and human sources in the area.
Door County's groundwater is extremely hard, which means you will see white, crusty scale buildup on pipes, faucets, and shower heads. Hard water makes soap less effective and can shorten the lifespan of water heaters and dishwashers. The mineral content may give your water a slightly salty or bitter taste. Scale can also clog fixtures and reduce water pressure over time.
We recommend testing your well water through a state-certified lab. Every well is different, and your well 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. A comprehensive metals and minerals panel runs $200-400 and should include testing for arsenic, lead, and PFOS/PFHXS. Treatment options like activated carbon filters or reverse osmosis systems can remove many of these contaminants.
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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