San Bernardino County, CA
These figures come from wells tested in San Bernardino County, CA, not from any one well.
- Sulfate is common in wells in San Bernardino County, CA (89 of 689 tested wells were over that level), so it's worth testing for.
- Iron and manganese are not common in wells in San Bernardino County, CA (8 of 206 and 10 of 206 tested wells were over). Only a test tells you about your own well.
- Wells in San Bernardino County, CA are typically hard (618 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:
- sulfate (common in wells here)
- iron
- manganese
- 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 | 3.9% |
| Wells over the level / wells judged | 8 of 206 |
| Median | 0.00715 mg/L |
| Years sampled | 1916–2026 |
| Wells | 206 |
| Test results | 1,586 |
| Wells left out | 1,318 |
| Sources | USGS (488) |
Manganese Recent
| Level it's compared with | 0.05 mg/L |
|---|---|
| Share of wells over the level | 4.9% |
| Wells over the level / wells judged | 10 of 206 |
| Median | 0.000935 mg/L |
| Years sampled | 1932–2026 |
| Wells | 206 |
| Test results | 1,090 |
| Wells left out | 1,199 |
| Sources | USGS (376) |
Hardness Recent
| Level it's compared with | none; hardness is shown in bands |
|---|---|
| Share of wells very hard | 44% |
| Median | 160 mg/L as CaCO₃ |
| Years sampled | 1908–2026 |
| Wells | 618 |
| Test results | 2,461 |
| Wells left out | 1,481 |
| Sources | USGS (618) |
Sulfate Recent
| Level it's compared with | 250 mg/L |
|---|---|
| Share of wells over the level | 13% |
| Wells over the level / wells judged | 89 of 689 |
| Median | 76 mg/L |
| Years sampled | 1908–2026 |
| Wells | 689 |
| Test results | 2,431 |
| Wells left out | 1,497 |
| Sources | USGS (689) |