Groundwater in San Diego County contains radon, manganese, iron, arsenic, boron, chloride, fluoride, lead, nitrate, perchlorate, PFAS compounds, sulfate, and uranium. Many of these contaminants exceed federal health standards, making them a serious concern for well owners in this county.
San Diego County sits on mixed rock types that naturally contain arsenic, uranium, and radon. Urban and agricultural activity adds nitrate and perchlorate to groundwater. Salt water intrusion near the coast increases chloride. Boron and fluoride come from natural rock dissolution. These contaminants accumulate because the local groundwater moves slowly through rock layers.
Groundwater in this county is very hard, driven by elevated calcium and magnesium from the surrounding rock, along with high sodium and moderate sulfate that add to the mineral load. The rock composition in this region naturally produces these dissolved minerals as water filters through it over time. These characteristics are widespread across wells throughout the county.
Wells in San Diego County commonly contain arsenic, uranium, radon, lead, nitrate, perchlorate, and forever chemicals like PFOA and PFOS at levels above EPA health standards. Arsenic and uranium damage kidneys and bones over time. Lead harms children's brains and development. Radon increases lung cancer risk. Nitrate and perchlorate affect thyroid function. Forever chemicals build up in your body and are linked to serious health issues.
The county's water is extremely hard with high sodium and sulfate levels. You will likely see white scale buildup on faucets and shower heads, staining on fixtures, and reduced water flow. Hard water shortens the lifespan of water heaters and dishwashers. Your soap won't lather well, and clothes and hair may feel sticky after washing.
Testing is the only way to know what is actually in your well since every well is different. We recommend a comprehensive panel that checks for metals, minerals, bacteria, and chemicals, which typically costs $200 to $400. Your well may have higher or lower levels than the county average. Water softening and activated carbon filters can help address these concerns once you know your specific situation.
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 | 80 | 60% | Moderate | High ⓘ | |
| Manganese | 1405 | 36% | High | High | |
| Iron | 2106 | 18% | High | High | |
| Chloride | 144 | 15% | High | High | |
| Sulfate | 144 | 12% | High | Moderate | |
| Uranium | 166 | 10% | High | Moderate | |
| Arsenic | 603 | 6% | High | Moderate | |
| Nitrate | 2360 | 5% | High |
Moderate
Elevated concentration, not % above limit
|
|
| PFOA ⓘ municipal | 163 | 4% | High |
Moderate
Elevated concentration, not % above limit
|
|
| PFOS ⓘ municipal | 163 | 4% | High |
Moderate
Elevated concentration, not % above limit
|
|
| Perchlorate | 144 | 3% | High | Low | |
| Boron | 144 | 3% | High | Low | |
| PFHxS ⓘ municipal | 163 | 1% | High | Low | |
| Lead | 319 | 1% | High | Low | |
| PFNA ⓘ municipal | 163 | 1% | High | Low | |
| Fluoride | 2810 | 0% | High | Low | |
| Nitrite | 574 | 0% | High | Low | |
| HFPO-DA (GenX) ⓘ municipal | 163 | 0% | High | Safe | |
| Chromium (total) | 144 | 0% | High | Low | |
| 1,2,3-Trichloropropane | 7 | 0% | Low | Safe ⓘ | |
| Radium 226 | 53 | 0% | Moderate | Low | |
| Radium 228 | 53 | 0% | Moderate | Low | |
| pH | 144 | — | High | Low | |
| Tds | 144 | — | High | Low | |
| PFBS ⓘ municipal | 163 | — | High | Low | |
| Sodium | 3299 | — | High | Low | |
| Hardness | 3558 | — | High | 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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