Groundwater in Lassen County contains radon, manganese, nitrate, arsenic, chloride, fluoride, iron, and sulfate at levels that exceed EPA health standards. Several of these contaminants--including arsenic, radon, and nitrate--present health concerns that well owners should monitor.
The volcanic rock beneath this county naturally releases arsenic, fluoride, and manganese into groundwater as water moves through the stone. Radon comes from decay of uranium in the rock itself. Nitrate typically enters from agricultural activity or septic systems in the area. Chloride and sulfate are also released by the rock and accumulate as water sits underground.
Groundwater in this county is moderately hard and carries elevated sodium and dissolved minerals, driven by the volcanic rock's composition and the buildup of salts over time in the groundwater. These mineral concentrations are widespread across wells in the county due to the common geology throughout the region.
Wells in Lassen County show several contaminants that exceed EPA health standards. Arsenic, fluoride, nitrate, and radon are found at concerning levels in county wells. Arsenic builds up in your body and increases the risk of cancer and heart disease. Nitrate is dangerous for babies and can cause serious illness. Radon is a radioactive gas that causes lung cancer when you breathe it over time. Fluoride at high levels can damage bones and teeth, especially in children.
The mineral content in county wells creates everyday problems for households. Your water has moderate sodium levels and is moderately hard, which means you'll likely see white scale buildup on faucets, showerheads, and inside pipes. Hard water reduces how well soap cleans clothes and skin. It shortens the lifespan of water heaters and dishwashers. You may notice a taste or odor from the high total dissolved solids in the water.
We recommend testing your well with a comprehensive panel that checks for metals, minerals, and all health contaminants found in the county. Every well is different--yours could have much higher or lower levels than what is common here. Testing is the only way to know what's actually in your water so you can treat it properly. A comprehensive panel usually costs between $200 and $400. Treatment options like reverse osmosis, activated carbon filters, or radon removal systems can address multiple concerns.
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 | 20 | 80% | Moderate | High ⓘ | |
| Manganese | 52 | 25% | Moderate | High | |
| Nitrate | 51 | 20% | Moderate | High | |
| Iron | 54 | 13% | Moderate | Moderate | |
| Arsenic | 54 | 9% | Moderate | Moderate | |
| Sulfate | 85 | 4% | Moderate |
Moderate
Elevated concentration, not % above limit
|
|
| Fluoride | 76 | 1% | Moderate | Low | |
| Chloride | 97 | 1% | Moderate | Low | |
| Perchlorate | 5 | 0% | Low | Low ⓘ | |
| Nitrite | 32 | 0% | Moderate | Low | |
| HFPO-DA (GenX) ⓘ municipal | 14 | 0% | Low | Safe | |
| PFOS ⓘ municipal | 14 | 0% | Low | Safe | |
| Uranium | 32 | 0% | Moderate | Low | |
| PFOA ⓘ municipal | 14 | 0% | Low | Safe | |
| PFNA ⓘ municipal | 14 | 0% | Low | Safe | |
| Boron | 5 | 0% | Low | Low ⓘ | |
| Chromium (total) | 5 | 0% | Low | Low ⓘ | |
| 1,2,3-Trichloropropane | 5 | 0% | Low | Safe ⓘ | |
| PFHxS ⓘ municipal | 14 | 0% | Low | Safe | |
| Lead | 40 | 0% | Moderate | Low | |
| Tds | 5 | — | Low | Low ⓘ | |
| Total Coliform | 1* | 0% | Low | Low ⓘ | |
| pH | 119 | — | High | Low | |
| Sodium | 92 | — | Moderate | Low | |
| E. coli | 1* | 0% | Low | Low ⓘ | |
| Hardness | 97 | — | Moderate | Low | |
| PFBS ⓘ municipal | 14 | — | Low | Safe |
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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