Groundwater in Washtenaw County contains iron, manganese, arsenic, nitrate, chloride, and sulfate. Several of these contaminants exceed federal health standards, which is concerning and warrants testing.
The Marshall aquifer beneath this county is sandstone that naturally contains iron and manganese. As groundwater moves slowly through this rock in low-oxygen conditions deep underground, these metals dissolve into the water. Arsenic is also locked naturally inside this same sandstone. Nitrate and chloride enter from fertilizer, septic systems, and road salt spread on highways and roads.
Groundwater in this county is very hard, driven by elevated calcium and magnesium from the rock layers below. Iron concentration in the water is very high, and the water also carries moderate levels of sodium. These mineral-rich characteristics are common across wells in Washtenaw County.
Wells in Washtenaw County commonly exceed EPA health standards for arsenic, nitrate, manganese, and iron. Arsenic is a poison that builds up in your body over years of drinking it and raises your risk of cancer and other serious illnesses. Nitrate is especially dangerous for infants and can interfere with how blood carries oxygen. Manganese harms brain development in children and can affect learning and behavior. Iron and chloride at high levels in county wells do not pose direct health risks, but they create serious quality-of-life problems.
The very hard water in this county causes mineral buildup that damages your home. Iron stains sinks, toilets, and laundry orange-brown and leaves a metallic taste. Manganese creates dark brown or black stains. The combination of high mineral content shortens the lifespan of water heaters, dishwashers, and other appliances by coating them with scale inside.
We recommend testing your well water because every well is different and yours may have higher or lower levels than what is common in the county. Testing is the only way to know what is actually in your water so it can be properly treated. Because multiple contaminants exceed health standards here, a comprehensive metals and minerals panel is recommended and typically costs $200-400. Treatment options like reverse osmosis systems and oxidation filters can address multiple concerns at once.
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 | 215 | 80% | High | High | |
| Manganese | 65 | 32% | Moderate | High | |
| Arsenic | 45 | 22% | Moderate | High | |
| Chloride | 225 | 4% | High |
Moderate
Elevated concentration, not % above limit
|
|
| Sulfate | 220 | 3% | High | Low | |
| Nitrate | 204 | 0% | High | Low | |
| Fluoride | 69 | 0% | Moderate | Low | |
| HFPO-DA (GenX) ⓘ municipal | 36 | 0% | Moderate | Safe | |
| Lead | 31 | 0% | Moderate | Low | |
| Nitrite | 48 | 0% | Moderate | Low | |
| PFHxS ⓘ municipal | 36 | 0% | Moderate | Safe | |
| PFNA ⓘ municipal | 36 | 0% | Moderate | Safe | |
| PFOA ⓘ municipal | 36 | 0% | Moderate | Safe | |
| PFOS ⓘ municipal | 36 | 0% | Moderate | Safe | |
| Radon | 11 | 0% | Low | Low ⓘ | |
| Uranium | 28 | 0% | Moderate | Low | |
| E. coli | 2* | 0% | Low | Low ⓘ | |
| Hardness | 225 | — | High | Low | |
| PFBS ⓘ municipal | 36 | — | Moderate | Safe | |
| pH | 232 | — | High | Low | |
| Sodium | 74 | — | Moderate | Low | |
| Total Coliform | 2* | 0% | Low | 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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