493 well testing events are on record for Monterey County, California. The primary contaminants detected are Radon, Hexavalent Chromium, Manganese.
Private well owners are responsible for their own water quality. Annual testing is recommended. See testing recommendations for Monterey County.
| Contaminant | Samples ⓘ | % Above MCL ⓘ | Distribution ⓘ | Confidence ⓘ | Risk ⓘ |
|---|---|---|---|---|---|
| Radon | 76 | 55% | Moderate | High ⓘ | |
| Hexavalent Chromium | 13 | 31% | Low | High | |
| Sulfate | 416 | 18% | High | High | |
| Manganese | 219 | 16% | High | High | |
| Nitrate | 221 | 15% | High | High | |
| Chloride | 416 | 14% | High | Moderate | |
| Perchlorate | 142 | 7% | High | Moderate | |
| Arsenic | 409 | 7% | High | Moderate | |
| Iron | 222 | 5% | High |
Moderate
Elevated concentration, not % above limit
|
|
| Boron | 142 | 5% | High |
Moderate
Elevated concentration, not % above limit
|
|
| Nitrite | 220 | 2% | High | Low | |
| PFOS ⓘ municipal | 165 | 2% | High | Low | |
| Uranium | 214 | 1% | High | Low | |
| PFOA ⓘ municipal | 165 | 1% | High | Low | |
| Lead | 195 | 1% | High | Low | |
| Fluoride | 415 | 0% | High | Low | |
| PFHxS ⓘ municipal | 165 | 0% | High | Low | |
| PFNA ⓘ municipal | 165 | 0% | High | Safe | |
| Radium 228 | 78 | 0% | Moderate | Low | |
| Chromium (total) | 142 | 0% | High | Low | |
| 1,2,3-Trichloropropane | 143 | 0% | High | Low | |
| Radium 226 | 78 | 0% | Moderate | Low | |
| HFPO-DA (GenX) ⓘ municipal | 165 | 0% | High | Safe | |
| Tds | 142 | — | High | Low | |
| Sodium | 415 | — | High | Low | |
| Hardness | 416 | — | High | Low | |
| Total Coliform | 8* | 0% | Low | Low ⓘ | |
| PFBS ⓘ municipal | 165 | — | High | Low | |
| pH | 418 | — | High | Low | |
| E. coli | 8* | 0% | 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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