Groundwater in Olmsted County contains iron, nitrate, and chloride at levels high enough to exceed EPA health standards. These contaminants are present in amounts that well owners should monitor, though the iron level itself is moderate.
Iron, nitrate, and chloride come from different sources in this county. Iron occurs naturally as water moves through the limestone and rock layers underground. Nitrate and chloride typically come from fertilizer use on farms and roads, which seep down into the groundwater over time.
Groundwater in this county is very hard, driven by elevated calcium and magnesium dissolved from the limestone bedrock. As water flows through the carbonate rock layers, it picks up these minerals easily because limestone dissolves in slightly acidic water. Very high hardness is common across wells throughout Olmsted County.
Wells in Olmsted County commonly contain chloride, iron, nitrate, and nitrite at levels that exceed EPA health standards. Nitrate and nitrite can interfere with how your blood carries oxygen, which is especially concerning for infants and pregnant women. Chloride at elevated levels can be a problem for people on sodium-restricted diets. Iron in drinking water, while less of a direct health concern at the levels found here, still warrants attention.
The very hard water in county wells creates real everyday problems. Hard water leaves stubborn scale on faucets, shower heads, and inside pipes. It makes soap less effective for cleaning and can leave spots on dishes and glassware. Over time, the mineral buildup in water heaters and dishwashers can shorten how long these appliances last. You may also notice a metallic or unpleasant taste from the iron content.
We recommend testing your well water with a comprehensive panel since multiple analytes exceed health standards in this county. Every well is different, and your water could have higher or lower levels than what is common here. Testing is the only way to know what is actually in your well so you can treat it properly. A comprehensive metals and minerals panel typically costs between $200 and $400. Water softeners and iron filters are common treatment options for 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 | 368 | 25% | High | High | |
| Manganese | 262 | 10% | High | Moderate | |
| Nitrate | 200 | 6% | High | Moderate | |
| Lead | 222 | 2% | High | Low | |
| Chloride | 452 | 2% | High | Low | |
| PFNA ⓘ municipal | 79 | 1% | Moderate | Low | |
| Arsenic | 222 | 0% | High | Low | |
| Fluoride | 191 | 0% | High | Low | |
| HFPO-DA (GenX) ⓘ municipal | 77 | 0% | Moderate | Safe | |
| Nitrite | 162 | 0% | High | Low | |
| PFHxS ⓘ municipal | 68 | 0% | Moderate | Low | |
| PFOA ⓘ municipal | 77 | 0% | Moderate | Low | |
| PFOS ⓘ municipal | 77 | 0% | Moderate | Safe | |
| Radon | 1 | 0% | Low | Low ⓘ | |
| Sulfate | 357 | 0% | High | Low | |
| Uranium | 1 | 0% | Low | Low ⓘ | |
| Sodium | 339 | — | High | Low | |
| pH | 222 | — | High | Low | |
| PFBS ⓘ municipal | 68 | — | Moderate | Safe | |
| Hardness | 142 | — | 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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