Groundwater in El Dorado County contains arsenic, chloride, iron, lead, manganese, nitrate, PFOA, PFOS, radon, sulfate, and uranium. Multiple contaminants exceed EPA health standards, making this a serious concern for well owners in the county.
These contaminants come from the local rock and soil mixed with human activity. The basin-fill geology here contains natural minerals like iron and arsenic that dissolve into groundwater. Nitrate and chloride seep down from agricultural land and road salt use. PFOA and PFOS are human-made chemicals that have spread through the water from industrial and commercial sites.
Groundwater in El Dorado County is moderately hard and notably high in iron. The rock layers below contain iron-rich minerals that naturally leach into the water as it flows underground. This combination of hardness and iron concentration shows up in wells across much of the county.
Wells in El Dorado County show a wide range of contaminants exceeding EPA health standards. Arsenic, uranium, and radon are radioactive elements that can increase cancer risk with long-term exposure. Lead and nitrate harm children's brain development and can cause serious health problems even at low levels. Pfoa and pfos are industrial chemicals that can affect liver function and the immune system. Chloride and sulfate at high levels may cause digestive issues for some people.
The high iron levels in county wells create visible staining on sinks, toilets, and laundry. Iron and manganese together can leave rust-colored or dark stains that are hard to remove. The moderately hard water means scale buildup on faucets and inside pipes and appliances. Over time, this scale can shorten the lifespan of water heaters and dishwashers.
Because El Dorado County wells have many different contaminants, we recommend a comprehensive water test to see what is actually in your well. Every well is different, and yours could have higher or lower levels than the county average--testing is the only way to know for sure. A full metals and minerals panel costs between $200 and $400. Treatment options like reverse osmosis systems, activated carbon filters, or ion exchange can address multiple concerns depending on what your test 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 | 711 | 41% | High | High | |
| Iron | 727 | 36% | High | High | |
| PFOA ⓘ municipal | 62 | 6% | Moderate | Moderate | |
| Radon | 68 | 4% | Moderate |
Moderate
ⓘ
Elevated concentration, not % above limit
|
|
| Arsenic | 593 | 4% | High |
Moderate
Elevated concentration, not % above limit
|
|
| PFOS ⓘ municipal | 62 | 3% | Moderate |
Moderate
Elevated concentration, not % above limit
|
|
| Nitrate | 544 | 2% | High | Low | |
| Uranium | 210 | 1% | High | Low | |
| Lead | 564 | 1% | High | Low | |
| Sulfate | 711 | 0% | High | Low | |
| Chloride | 721 | 0% | High | Low | |
| PFNA ⓘ municipal | 62 | 0% | Moderate | Safe | |
| PFHxS ⓘ municipal | 62 | 0% | Moderate | Low | |
| Nitrite | 151 | 0% | High | Low | |
| HFPO-DA (GenX) ⓘ municipal | 60 | 0% | Moderate | Safe | |
| Fluoride | 713 | 0% | High | Low | |
| Perchlorate | 40 | 0% | Moderate | Low | |
| Boron | 41 | 0% | Moderate | Low | |
| Chromium (total) | 441 | 0% | High | Low | |
| 1,2,3-Trichloropropane | 251 | 0% | High | Safe | |
| Tds | 441 | — | High | Low | |
| pH | 1163 | — | High | Low | |
| Total Coliform | 34* | 0% | Moderate | Low | |
| PFBS ⓘ municipal | 62 | — | Moderate | Low | |
| Sodium | 712 | — | High | Low | |
| Hardness | 711 | — | High | Low | |
| E. coli | 34* | 0% | Moderate | 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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