Groundwater in Winnebago County contains iron, manganese, nitrate, and sulfate at levels high enough to exceed EPA health standards. These contaminants require attention from well owners.
The deep rock layers beneath this county naturally release iron and manganese as water sits in contact with them over time. Sulfate accumulates in the groundwater through the same slow dissolution process. Nitrate can enter from both natural sources in the rock and from land uses like agriculture and septic systems.
Groundwater in this county is very hard, driven by elevated calcium and magnesium that dissolve from the rock below. The water also carries iron at high levels. These characteristics show up across wells throughout the county.
Iron, manganese, nitrate, and sulfate are found at levels exceeding EPA health standards in wells across Winnebago County. Iron and manganese can cause problems with blood and organs when ingested over time. Nitrate is especially dangerous for infants and can interfere with oxygen in the blood. Sulfate can cause digestive issues in some people, particularly children and those with sensitivities.
The water in this county is very hard, and you will see white, crusty scale buildup on faucets, showerheads, and inside pipes and appliances. Iron staining leaves orange-brown marks on sinks, bathtubs, and laundry. Hard water this severe can shorten the lifespan of water heaters and dishwashers. You may notice that soap doesn't work as well and your water has a metallic or unpleasant taste.
Testing your well is the only way to know what is actually in your water so it can be properly treated. Every well in the county is different, and your well may have higher or lower levels than what is common here. We recommend a comprehensive metals and minerals panel, which typically costs between two hundred and four hundred dollars. Iron removal systems and water softeners 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 | 74 | 77% | Moderate | High | |
| Sulfate | 73 | 34% | Moderate | High | |
| Manganese | 39 | 15% | Moderate | High | |
| Nitrate | 35 | 6% | Moderate | Moderate | |
| Arsenic | 12 | 0% | Low | Low | |
| Chloride | 73 | 0% | Moderate | Low | |
| Fluoride | 38 | 0% | Moderate | Low | |
| HFPO-DA (GenX) ⓘ municipal | 37 | 0% | Moderate | Safe | |
| Lead | 13 | 0% | Low | Low | |
| Nitrite | 19 | 0% | Moderate | Low | |
| PFHxS ⓘ municipal | 37 | 0% | Moderate | Low | |
| PFNA ⓘ municipal | 37 | 0% | Moderate | Safe | |
| PFOA ⓘ municipal | 37 | 0% | Moderate | Low | |
| PFOS ⓘ municipal | 37 | 0% | Moderate | Low | |
| Radon | 8 | 0% | Low | Low ⓘ | |
| Uranium | 7 | 0% | Low | Low ⓘ | |
| Hardness | 74 | — | Moderate | Low | |
| pH | 81 | — | Moderate | Low | |
| Sodium | 56 | — | Moderate | Low | |
| PFBS ⓘ municipal | 37 | — | 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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