Groundwater in San Bernardino County contains radon, arsenic, sulfate, and many other contaminants at levels that exceed EPA health standards. These are serious concerns that require attention from well owners in this area.
San Bernardino County sits in a geologically complex region where rock layers trap and concentrate minerals and contaminants from both natural sources and human activity. Arsenic and uranium come from the rock itself as water slowly dissolves minerals underground over time. Radon gas enters groundwater from radioactive elements in the surrounding rock. Nitrate, chloride, and other contaminants seep down from the land surface through agricultural use, urban development, and septic systems. Perfluorinated chemicals like PFOA and PFOS come from industrial and commercial sources that have contaminated shallow groundwater in some areas.
Groundwater in this county is hard, driven by elevated calcium and magnesium from the rock layers below, and it carries high levels of sodium and moderate sulfate. The combination of these minerals reflects water moving slowly through varied rock types that dissolve and release dissolved solids over long periods. These mineral characteristics are widespread across wells throughout San Bernardino County.
Wells in San Bernardino County commonly exceed EPA health standards for arsenic, boron, chloride, fluoride, lead, nitrate, uranium, radon, and PFOA and PFOS chemicals. Arsenic and uranium are linked to cancer risk with long-term exposure. Lead damages children's brains and kidneys. Nitrate and nitrite harm infants and can affect thyroid function. Radon increases lung cancer risk when inhaled over time.
Hard water in county wells causes white scale buildup on fixtures and inside pipes. You may notice staining on sinks and showers, soap that doesn't lather well, and cloudy spots on dishes. Hard water can shorten the lifespan of water heaters and dishwashers by years. The high sodium and sulfate levels can affect the taste of your water.
We recommend a comprehensive water test since multiple contaminants exceed health standards in this county. Every well is different, and yours could have higher or lower levels than what is common here. 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 $200 to $400 and can identify which contaminants need treatment, such as carbon filters for chemicals or water softeners for hardness.
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 | 153 | 44% | High | High ⓘ | |
| Arsenic | 4294 | 23% | High | High | |
| Sulfate | 8687 | 13% | High | Moderate | |
| Manganese | 5307 | 9% | High | Moderate | |
| Boron | 60 | 8% | Moderate | Moderate | |
| Fluoride | 8263 | 8% | High | Moderate | |
| Uranium | 1129 | 8% | High | Moderate | |
| PFOS ⓘ municipal | 765 | 7% | High | Moderate | |
| Nitrate | 59 | 7% | Moderate | Moderate | |
| Chloride | 9241 | 7% | High | Moderate | |
| Iron | 6746 | 6% | High | Moderate | |
| PFOA ⓘ municipal | 765 | 5% | High | Moderate | |
| PFHxS ⓘ municipal | 758 | 3% | High | Low | |
| Nitrite | 4957 | 1% | High | Low | |
| Lead | 1390 | 0% | High | Low | |
| HFPO-DA (GenX) ⓘ municipal | 760 | 0% | High | Safe | |
| Chromium (total) | 61 | 0% | Moderate | Low | |
| 1,2,3-Trichloropropane | 67 | 0% | Moderate | Low | |
| Perchlorate | 68 | 0% | Moderate | Low | |
| PFNA ⓘ municipal | 765 | 0% | High | Low | |
| Tds | 60 | — | Moderate | Low | |
| PFBS ⓘ municipal | 760 | — | High | Low | |
| Sodium | 8336 | — | High | Low | |
| Hardness | 8645 | — | High | Low | |
| E. coli | 71* | 0% | Moderate | Low | |
| pH | 9439 | — | High | Low | |
| Total Coliform | 71* | 0% | 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.
Loading recent water news…