Groundwater in Humboldt County contains arsenic, iron, lead, manganese, nitrate, radon, and sulfate at levels that exceed EPA health standards. These contaminants are present at concerning levels and warrant attention from well owners in this area.
The rocks beneath Humboldt County naturally contain metals like iron, manganese, and arsenic that dissolve into groundwater as water moves through the earth. Radon comes from natural radioactive decay in the rock itself. Nitrate can come from soil and septic systems, while sulfate occurs naturally in certain rock layers. This mix of natural geology and land use creates the contamination pattern seen across the county.
Groundwater in Humboldt County is hard, driven mainly by elevated iron and hardness minerals from the local rocks. The volcanic and metamorphic rocks in this region break down slowly and release these minerals into the water over time. Hard water with elevated iron is common across wells throughout the county.
Wells in this county can have arsenic, lead, radon, and nitrate at levels that exceed EPA health standards, along with elevated iron and manganese. Arsenic and lead are especially concerning because they can build up in your body over time and cause serious health problems including cancer and nervous system damage. Radon is a radioactive gas that enters water from underground rocks and can increase lung cancer risk. Nitrate is dangerous for babies and can interfere with how blood carries oxygen.
The hard water in county wells leaves visible stains on fixtures and dishes, and causes scale buildup inside pipes and appliances. This scale can shorten the lifespan of water heaters and dishwashers. Iron in the water can cause brown or reddish staining on sinks and laundry. You may notice an unpleasant taste or smell from the mineral content.
We recommend testing your well water with a comprehensive panel since multiple analytes exceed health standards in this county, and every well is different. Your well could have higher or lower levels than what is common here, and testing is the only way to know what is actually in your water so you can treat it properly. A comprehensive metals and minerals panel typically costs between two hundred and four hundred dollars. Treatment options like reverse osmosis or activated carbon filters can address different contaminants depending on what testing shows.
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 | 117 | 71% | High | High | |
| Iron | 171 | 57% | High | High | |
| Radon | 21 | 33% | Moderate | High ⓘ | |
| Sulfate | 204 | 23% | High | High | |
| Nitrate | 7 | 14% | Low | Moderate ⓘ | |
| Lead | 57 | 9% | Moderate | Moderate | |
| Arsenic | 47 | 2% | Moderate | Low | |
| Chloride | 7 | 0% | Low | Low ⓘ | |
| PFOS ⓘ municipal | 26 | 0% | Moderate | Safe | |
| Fluoride | 149 | 0% | High | Low | |
| HFPO-DA (GenX) ⓘ municipal | 23 | 0% | Moderate | Safe | |
| Nitrite | 47 | 0% | Moderate | Low | |
| Perchlorate | 4 | 0% | Low | Safe ⓘ | |
| PFOA ⓘ municipal | 26 | 0% | Moderate | Low | |
| Uranium | 47 | 0% | Moderate | Low | |
| Boron | 7 | 0% | Low | Low ⓘ | |
| Chromium (total) | 7 | 0% | Low | Low ⓘ | |
| 1,2,3-Trichloropropane | 4 | 0% | Low | Safe ⓘ | |
| PFHxS ⓘ municipal | 26 | 0% | Moderate | Low | |
| PFNA ⓘ municipal | 26 | 0% | Moderate | Safe | |
| pH | 7 | — | Low | Low ⓘ | |
| Tds | 7 | — | Low | Low ⓘ | |
| Total Coliform | 14* | 0% | Low | Low | |
| Hardness | 222 | — | High | Low | |
| E. coli | 14* | 0% | Low | Low | |
| Sodium | 218 | — | High | Low | |
| PFBS ⓘ municipal | 26 | — | 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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