San Diego County, CA
These figures come from wells tested in San Diego County, CA, not from any one well.
- Iron is common in wells in San Diego County, CA (5 of 19 tested wells were over that level), so it's worth testing for.
- Manganese is common in wells in San Diego County, CA (4 of 16 tested wells were over that level), so it's worth testing for.
- Sulfate is common in wells in San Diego County, CA (66 of 264 tested wells were over that level), so it's worth testing for.
- Wells in San Diego County, CA are typically very hard (269 wells tested).
- Only a test of your own well tells you about your water.
What to test for
Start with the four this site covers:
- iron (common in wells here)
- manganese (common in wells here)
- sulfate (common in wells here)
- hardness
Most well owners also test for these. We point to the source and don't interpret the results.
- arsenic: occurs naturally in groundwater in many regions. USGS: arsenic and drinking water
- nitrate: common near farmland and septic systems. EPA: private drinking water wells
- total coliform bacteria: the standard yearly well check. EPA: private drinking water wells
- lead and copper: from household plumbing, especially when pH is below 6.5. EPA: lead in drinking water
- PFAS: several states run private-well sampling programs. EPA: PFAS
- a certified lab: states certify labs and some run their own private-well programs. California's certified-lab list (from your state drinking-water program)
The numbers
County figures describe the wells sampled there, not any one well. Exact counts, sample years and sources are below.
Iron Recent
| Level it's compared with | 0.3 mg/L |
|---|---|
| Share of wells over the level | 26% |
| Wells over the level / wells judged | 5 of 19 |
| Median | 0.00845 mg/L |
| Years sampled | 1948–2022 |
| Wells | 19 |
| Test results | 391 |
| Wells left out | 460 |
| Sources | USGS (197), LPEPA106 (3) |
Manganese Recent
| Level it's compared with | 0.05 mg/L |
|---|---|
| Share of wells over the level | 25% |
| Wells over the level / wells judged | 4 of 16 |
| Median | 0.006425 mg/L |
| Years sampled | 1948–2017 |
| Wells | 16 |
| Test results | 182 |
| Wells left out | 402 |
| Sources | USGS (103) |
Hardness Recent
| Level it's compared with | none; hardness is shown in bands |
|---|---|
| Share of wells very hard | 67% |
| Median | 273 mg/L as CaCO₃ |
| Years sampled | 1939–2022 |
| Wells | 269 |
| Test results | 685 |
| Wells left out | 668 |
| Sources | USGS (268), LPEPA106 (1) |
Sulfate Recent
| Level it's compared with | 250 mg/L |
|---|---|
| Share of wells over the level | 25% |
| Wells over the level / wells judged | 66 of 264 |
| Median | 97.75 mg/L |
| Years sampled | 1915–2022 |
| Wells | 264 |
| Test results | 633 |
| Wells left out | 625 |
| Sources | USGS (261), LPEPA106 (3) |