Groundwater in Mahnomen County contains arsenic, iron, and manganese at levels that exceed EPA health standards. All three contaminants are present at concerning concentrations that warrant your attention.
These metals come from the rock itself. The stone underneath this county naturally contains iron and manganese, which dissolve into groundwater as it moves through the ground. Arsenic also occurs naturally in these rocks and leaches into water over time.
Groundwater in this county is very hard, driven by elevated calcium and magnesium from the rock below. The same stone that releases iron and manganese also contributes minerals that make the water hard. Most wells in Mahnomen County show these same characteristics.
Arsenic, iron, and manganese are found at unhealthy levels in wells across Mahnomen County. Arsenic is a poison that builds up in your body over time and can cause cancer and damage to your kidneys and nervous system. Manganese can affect your brain development and learning, especially in children. Iron at high levels may also pose health concerns. Your well water could contain any of these contaminants at dangerous amounts.
The water in Mahnomen County is extremely hard, which means you will see white or rust-colored scale buildup inside pipes and on fixtures. Reddish or brown staining appears on laundry, sinks, and bathtubs from the high iron levels. Hard water also makes soap work poorly, leaving spots on dishes and dull residue on skin and hair. Very hard water shortens the lifespan of water heaters, dishwashers, and washing machines because scale clogs the equipment.
We recommend getting your well tested right away. Every well is different, and your water could have much higher or much lower levels than what is common in the county. A comprehensive metals and minerals panel costs around $200 to $400 and is the only way to find out exactly what is in your water so you can treat it properly. Treatment systems for arsenic removal and iron and manganese filtration are available once you know your results.
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 ⓘ |
|---|---|---|---|---|---|
| Manganese | 19 | 95% | Moderate | High | |
| Iron | 19 | 79% | Moderate | High | |
| Arsenic | 8 | 50% | Low | High ⓘ | |
| Radon | 4 | 0% | Low | Low ⓘ | |
| Nitrite | 4 | 0% | Low | Safe ⓘ | |
| PFNA | 1 | 0% | Low | Low ⓘ | |
| PFOA | 1 | 0% | Low | Low ⓘ | |
| PFOS | 1 | 0% | Low | Low ⓘ | |
| Chloride | 18 | 0% | Moderate | Low | |
| Fluoride | 13 | 0% | Low | Low | |
| Lead | 10 | 0% | Low | Safe | |
| Nitrate | 13 | 0% | Low | Low | |
| Sulfate | 19 | 0% | Moderate | Low | |
| Uranium | 4 | 0% | Low | Low ⓘ | |
| Sodium | 13 | — | Low | Low | |
| Hardness | 17 | — | Moderate | Low | |
| pH | 17 | — | 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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