Groundwater in Chittenden County contains arsenic, chloride, fluoride, iron, lead, manganese, nitrate, radon, and uranium--all at levels exceeding EPA health standards. These contaminants are present at concentrations serious enough that well owners should test and consider treatment.
Limestone bedrock beneath the county naturally releases calcium, magnesium, iron, and manganese as water moves through it over time. Radon seeps into groundwater from radioactive minerals in the rock itself. Road salt, fertilizers, and other human activities add chloride, nitrate, and lead to the water; uranium and arsenic also occur naturally in the limestone and surrounding rock layers.
Groundwater in this county is very hard, driven by elevated calcium and magnesium dissolving from the limestone aquifer below. The carbonate rock that supplies wells here readily releases these minerals as water filters down through fractures and layers. Very hard water is the normal condition across most wells in Chittenden County.
Wells in Chittenden County exceed EPA health standards for arsenic, lead, uranium, radon, nitrate, and fluoride. Arsenic and lead damage organs over time and raise cancer risk. Uranium and radon are radioactive and increase cancer risk. Nitrate harms infants and people with certain conditions. Fluoride at very high levels can damage bones and teeth.
The water in this county is very hard, which causes mineral scale buildup on pipes and fixtures and shortens the lifespan of water heaters and dishwashers. You may notice crusty buildup around faucets or in your shower. Hard water can make soap work poorly and leave spots on dishes and glassware.
We recommend testing your well with a comprehensive panel that covers metals, minerals, bacteria, and radioactive contaminants. Every well is different, and your well could have higher or lower levels than what is common here. Testing costs between $200 and $400 and is the only way to know what is actually in your water so you can treat it properly. Treatment options include activated carbon filters for some contaminants and reverse osmosis systems for others.
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 ⓘ |
|---|---|---|---|---|---|
| Radon | 438 | 70% | High | High ⓘ | |
| Manganese | 2454 | 15% | High | High | |
| Iron | 2235 | 11% | High | Moderate | |
| Arsenic | 4485 | 4% | High |
Moderate
Elevated concentration, not % above limit
|
|
| Uranium | 4238 | 2% | High | Low | |
| Chloride | 3961 | 2% | High | Low | |
| Lead | 11370 | 1% | High | Low | |
| Nitrate | 4814 | 0% | High | Low | |
| Fluoride | 5063 | 0% | High | Low | |
| HFPO-DA (GenX) ⓘ municipal | 40 | 0% | Moderate | Safe | |
| Nitrite | 4755 | 0% | High | Low | |
| PFHxS ⓘ municipal | 40 | 0% | Moderate | Safe | |
| PFNA ⓘ municipal | 40 | 0% | Moderate | Safe | |
| PFOA ⓘ municipal | 40 | 0% | Moderate | Safe | |
| PFOS ⓘ municipal | 40 | 0% | Moderate | Safe | |
| Sulfate | 440 | 0% | High | Low | |
| Sodium | 2223 | — | High | Low | |
| pH | 1550 | — | High | Low | |
| PFBS ⓘ municipal | 40 | — | Moderate | Safe | |
| Hardness | 1796 | — | 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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