Well owners in Ontario County need to know about manganese, radon, sulfate, chloride, iron, and nitrate in their groundwater. Several of these contaminants exceed EPA health standards and require attention.
These contaminants come from the limestone bedrock that underlies the county and from human activities on the land. As water moves slowly through limestone, it dissolves minerals and can pick up chloride from road salt spread on winter roads. Radon seeps in from natural uranium decay in the rock. Nitrate enters from fertilizer and septic systems in soil above the water.
The water in Ontario County is very hard, driven primarily by calcium and magnesium from the limestone below. Moderate sulfate levels add to the mineral content. These characteristics are common across wells throughout the county, reflecting the shared geology of the carbonate-rock aquifer that supplies drinking water to the region.
Wells in Ontario County commonly exceed EPA health standards for chloride, iron, manganese, nitrate, radon, and sulfate. Radon is a radioactive gas that enters groundwater naturally and increases lung cancer risk when inhaled from water. Chloride at elevated levels can harm people with certain health conditions and affect kidney function. Nitrate poses serious risks to infants and pregnant women, interfering with oxygen transport in blood. Manganese can affect brain development in children and cause neurological problems at high exposure levels.
The county's water is very hard, which creates visible problems in daily life. Orange or brown staining appears in sinks, toilets, and on laundry from iron deposits. You will see white scale buildup inside pipes and on fixtures from mineral accumulation. Hard water makes soap less effective and leaves residue on skin and dishes. Over time, this mineral buildup can shorten the lifespan of water heaters, dishwashers, and other appliances.
We recommend testing your well with a comprehensive metals and minerals panel to find out exactly what is in your water, since every well is different and yours may have higher or lower levels than what is common here. Testing is the only way to know what needs treatment in your specific well. A comprehensive panel typically costs $200 to $400. Water softeners can address hardness, while radon removal systems and specific filters can treat other contaminants.
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 | 42 | 36% | Moderate | High | |
| Radon | 15 | 27% | Moderate | High ⓘ | |
| Sulfate | 65 | 26% | Moderate | High | |
| Iron | 45 | 20% | Moderate | High | |
| Chloride | 69 | 7% | Moderate | Moderate | |
| Nitrate | 46 | 2% | Moderate | Low | |
| Arsenic | 23 | 0% | Moderate | Low | |
| Fluoride | 44 | 0% | Moderate | Low | |
| HFPO-DA (GenX) ⓘ municipal | 42 | 0% | Moderate | Safe | |
| Lead | 22 | 0% | Moderate | Low | |
| Nitrite | 16 | 0% | Moderate | Low | |
| PFHxS ⓘ municipal | 42 | 0% | Moderate | Safe | |
| PFNA ⓘ municipal | 42 | 0% | Moderate | Safe | |
| PFOA ⓘ municipal | 42 | 0% | Moderate | Safe | |
| PFOS ⓘ municipal | 42 | 0% | Moderate | Safe | |
| Uranium | 15 | 0% | Moderate | Low | |
| E. coli | 8* | 0% | Low | Low ⓘ | |
| Fecal Coliform | 8* | 0% | Low | Low ⓘ | |
| Hardness | 69 | — | Moderate | Low | |
| PFBS ⓘ municipal | 42 | — | Moderate | Low | |
| pH | 69 | — | Moderate | Low | |
| Sodium | 45 | — | Moderate | Low | |
| Total Coliform | 8* | 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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