Groundwater in Winona County contains manganese, nitrate, iron, and chloride at levels that exceed EPA health standards. These contaminant concentrations are notable enough that well owners should be aware of them.
The limestone bedrock beneath this county naturally contains iron and manganese that dissolve into groundwater as water moves slowly through the rock layers. Nitrate and chloride come from land use--agricultural fertilizer and road salt seep down into the aquifer where they mix with groundwater over time.
Groundwater in this county is very hard, driven by calcium and magnesium dissolved from the limestone bedrock. The carbonate rock naturally releases these minerals into the water as it sits in contact with the ground layers. Very hard water is common across wells throughout Winona County.
Chloride, iron, manganese, and nitrate reach elevated levels in Winona County wells. Nitrate exposure is a concern for infants and can interfere with oxygen in the blood. Manganese at high levels can affect brain development, especially in children. Iron and chloride at elevated concentrations pose health risks with long-term exposure. Chloride itself is not toxic, but high levels can cause problems for people on salt-restricted diets.
Winona County has very hard water, which means mineral buildup on pipes and inside water heaters and dishwashers. This scale can shorten the lifespan of appliances. Iron in the water leaves rusty-brown stains on clothes, fixtures, and surfaces. The water may taste metallic or smell unpleasant from the iron and manganese.
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. We recommend a comprehensive metals and minerals panel to check for all four contaminants. A full panel typically costs between two hundred and four hundred dollars. Iron removal systems and nitrate treatment through reverse osmosis can help 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 | 153 | 36% | High | High | |
| PFOS ⓘ municipal | 21 | 10% | Moderate | Moderate | |
| Nitrate | 55 | 4% | Moderate |
Moderate
Elevated concentration, not % above limit
|
|
| Manganese | 117 | 3% | High |
Moderate
Elevated concentration, not % above limit
|
|
| Arsenic | 134 | 1% | High | Low | |
| Lead | 136 | 1% | High | Low | |
| Chloride | 190 | 0% | High | Low | |
| Fluoride | 168 | 0% | High | Low | |
| HFPO-DA (GenX) ⓘ municipal | 18 | 0% | Moderate | Safe | |
| Nitrite | 45 | 0% | Moderate | Safe | |
| PFHxS ⓘ municipal | 16 | 0% | Moderate | Safe | |
| PFNA ⓘ municipal | 18 | 0% | Moderate | Safe | |
| PFOA ⓘ municipal | 20 | 0% | Moderate | Low | |
| Radon | 1 | 0% | Low | Low ⓘ | |
| Sulfate | 179 | 0% | High | Low | |
| Uranium | 24 | 0% | Moderate | Low | |
| Hardness | 18 | — | Moderate | Low | |
| PFBS ⓘ municipal | 17 | — | Moderate | Low | |
| pH | 22 | — | Moderate | Low | |
| Sodium | 156 | — | 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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