Groundwater in Trinity County contains radon, PFOS, and iron at levels that exceed EPA health standards. These contaminants are present at concentrations that warrant attention, though they are not uniformly distributed across all wells in the county.
Radon comes from natural radioactive decay in the rock itself, particularly common in areas with granite and similar crystalline rocks. PFOS is a human-made chemical that enters groundwater through contamination from industrial sites, firefighting foam, or waste disposal. Iron dissolves naturally from minerals in the surrounding rock as water moves through it underground.
Groundwater in this county is hard, driven by dissolved calcium and magnesium from the rock formations beneath the surface. This hardness is a natural result of water passing through the mineral-rich geology of the region. Hard water is the most common characteristic found in wells across Trinity County, while elevated iron and radon vary more from well to well.
Wells in Trinity County commonly have iron, PFOS, and radon at levels above EPA health standards. Iron at high levels can cause problems with your blood and organs. PFOS is a human-made chemical that can affect your immune system, thyroid, and liver. Radon is a radioactive gas that increases the risk of lung cancer when you breathe it over time.
Hard water is common in county wells and can leave spots on dishes and fixtures. You might see rust-colored staining from iron in sinks and on laundry. Scale can build up inside pipes and water heaters, which shortens the lifespan of appliances like dishwashers and hot water heaters.
Testing is the only way to know what is actually in your well. We recommend a comprehensive panel since multiple contaminants exceed standards in this county--this typically costs $200 to $400. Your well may have higher or lower levels than what is common here. Treatment options like activated carbon filters and aeration systems can address these concerns once you know your specific water quality.
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 | 13 | 62% | Low | High ⓘ | |
| PFOS ⓘ municipal | 12 | 33% | Low | High | |
| Iron | 15 | 7% | Moderate | Moderate | |
| Fluoride | 16 | 0% | Moderate | Low | |
| HFPO-DA (GenX) ⓘ municipal | 12 | 0% | Low | Safe | |
| Nitrite | 16 | 0% | Moderate | Safe | |
| Chloride | 16 | 0% | Moderate | Low | |
| PFNA ⓘ municipal | 12 | 0% | Low | Safe | |
| PFHxS ⓘ municipal | 12 | 0% | Low | Low | |
| Nitrate | 16 | 0% | Moderate | Low | |
| Manganese | 12 | 0% | Low | Low | |
| Lead | 5 | 0% | Low | Low ⓘ | |
| Sulfate | 16 | 0% | Moderate | Low | |
| Uranium | 16 | 0% | Moderate | Low | |
| Boron | 1 | 0% | Low | Low ⓘ | |
| Arsenic | 16 | 0% | Moderate | Low | |
| Chromium (total) | 1 | 0% | Low | Low ⓘ | |
| 1,2,3-Trichloropropane | 1 | 0% | Low | Safe ⓘ | |
| PFOA ⓘ municipal | 12 | 0% | Low | Safe | |
| Tds | 1 | — | Low | Low ⓘ | |
| PFBS ⓘ municipal | 12 | — | Low | Safe | |
| pH | 16 | — | Moderate | Low | |
| Hardness | 16 | — | Moderate | Low | |
| Sodium | 16 | — | 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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