Los Angeles County, CA
These figures come from wells tested in Los Angeles County, CA, not from any one well.
- Iron is common in wells in Los Angeles County, CA (12 of 70 tested wells were over that level), so it's worth testing for.
- Manganese is common in wells in Los Angeles County, CA (20 of 74 tested wells were over that level), so it's worth testing for.
- Sulfate is common in wells in Los Angeles County, CA (16 of 158 tested wells were over that level), so it's worth testing for.
- Wells in Los Angeles County, CA are typically very hard (155 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 | 17% |
| Wells over the level / wells judged | 12 of 70 |
| Median | 0.0137 mg/L |
| Years sampled | 1908–2024 |
| Wells | 72 |
| Test results | 244 |
| Wells left out | 759 |
| Sources | USGS (96) |
Manganese Recent
| Level it's compared with | 0.05 mg/L |
|---|---|
| Share of wells over the level | 27% |
| Wells over the level / wells judged | 20 of 74 |
| Median | 0.00981 mg/L |
| Years sampled | 1981–2024 |
| Wells | 77 |
| Test results | 189 |
| Wells left out | 722 |
| Sources | USGS (92) |
Hardness Recent
| Level it's compared with | none; hardness is shown in bands |
|---|---|
| Share of wells very hard | 56% |
| Median | 200 mg/L as CaCO₃ |
| Years sampled | 1908–2024 |
| Wells | 155 |
| Test results | 540 |
| Wells left out | 842 |
| Sources | USGS (155) |
Sulfate Recent
| Level it's compared with | 250 mg/L |
|---|---|
| Share of wells over the level | 10% |
| Wells over the level / wells judged | 16 of 158 |
| Median | 64.0525 mg/L |
| Years sampled | 1908–2024 |
| Wells | 158 |
| Test results | 520 |
| Wells left out | 826 |
| Sources | USGS (158) |