Groundwater in Fond du Lac County contains iron, radon, sulfate, and chloride at levels that exceed EPA health standards. These contaminant levels are notable enough that well owners should be aware of them and consider testing.
These contaminants come from the deep rock layers beneath the county. Iron and sulfate dissolve naturally from the rock as groundwater moves slowly through it over many years. Chloride can come from both natural sources in the rock and from road salt that seeps down through soil in winter months. Radon, a radioactive gas, forms naturally in these deep rock layers.
Groundwater in this 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 rock layers for years, it picks up dissolved minerals that make it hard. Very hard water is common across most wells in Fond du Lac County.
Wells in Fond du Lac County commonly exceed EPA health standards for chloride, iron, radon, and sulfate. Chloride at elevated levels can affect people with high blood pressure or heart disease. Radon is a radioactive gas that increases lung cancer risk over time with long-term exposure. Iron and sulfate at these levels can cause digestive issues in some people, especially infants and those with certain health conditions.
The water in this county is very hard, which creates visible problems around the home. You may notice white, crusty scale buildup inside pipes and on fixtures like showerheads and faucets. Iron stains clothes, sinks, and fixtures with rust-colored marks that are hard to remove. Very hard water also shortens the lifespan of water heaters, dishwashers, and other appliances.
Testing is the only way to know what is actually in your well, since every well is different and your water may have higher or lower levels than what is common in the county. Because multiple analytes exceed health standards here, we recommend a comprehensive water test that checks for metals, minerals, and radon--typically costing $200-400. A water softener can reduce hardness, and iron removal systems or radon mitigation can address those specific 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 | 113 | 56% | High | High | |
| Radon | 5 | 20% | Low | High ⓘ | |
| Manganese | 106 | 16% | High | High | |
| Sulfate | 119 | 6% | High | Moderate | |
| Nitrate | 57 | 4% | Moderate |
Moderate
Elevated concentration, not % above limit
|
|
| Chloride | 120 | 1% | High | Low | |
| Arsenic | 9 | 0% | Low | Low ⓘ | |
| Fluoride | 107 | 0% | High | Low | |
| HFPO-DA (GenX) ⓘ municipal | 24 | 0% | Moderate | Safe | |
| Lead | 9 | 0% | Low | Low ⓘ | |
| Nitrite | 38 | 0% | Moderate | Low | |
| PFHxS ⓘ municipal | 24 | 0% | Moderate | Low | |
| PFNA ⓘ municipal | 24 | 0% | Moderate | Low | |
| PFOA ⓘ municipal | 24 | 0% | Moderate | Low | |
| PFOS ⓘ municipal | 24 | 0% | Moderate | Safe | |
| Uranium | 15 | 0% | Moderate | Low | |
| Hardness | 120 | — | High | Low | |
| PFBS ⓘ municipal | 24 | — | Moderate | Low | |
| pH | 119 | — | High | Low | |
| Sodium | 88 | — | Moderate | 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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