St. Louis County, MN
These figures come from wells tested in St. Louis County, MN, not from any one well.
- Iron is common in wells in St. Louis County, MN (75 of 200 tested wells were over that level), so it's worth testing for.
- Manganese is common in wells in St. Louis County, MN (109 of 189 tested wells were over that level), so it's worth testing for.
- Sulfate is not common in wells in St. Louis County, MN (2 of 346 tested wells were over). Only a test tells you about your own well.
- Wells in St. Louis County, MN are typically hard (345 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)
- hardness
- sulfate
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. Minnesota'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 | 38% |
| Wells over the level / wells judged | 75 of 200 |
| Median | 0.1705 mg/L |
| Years sampled | 1956–2025 |
| Wells | 200 |
| Test results | 542 |
| Wells left out | 1 |
| Sources | MNDNR_AGW (185), USGS (100), MNPCA_AGW (66) |
Manganese Recent
| Level it's compared with | 0.05 mg/L |
|---|---|
| Share of wells over the level | 58% |
| Wells over the level / wells judged | 109 of 189 |
| Median | 0.0847 mg/L |
| Years sampled | 1956–2025 |
| Wells | 189 |
| Test results | 525 |
| Wells left out | 1 |
| Sources | MNDNR_AGW (179), USGS (98), MNPCA_AGW (61) |
Hardness Recent
| Level it's compared with | none; hardness is shown in bands |
|---|---|
| Share of wells very hard | 33% |
| Median | 136.418 mg/L as CaCO₃ |
| Years sampled | 1956–2025 |
| Wells | 345 |
| Test results | 556 |
| Wells left out | 1 |
| Sources | MNDNR_AGW (183), USGS (99), MNPCA_AGW (61), MNPCA (2) |
Sulfate Recent
| Level it's compared with | 250 mg/L |
|---|---|
| Share of wells over the level | 0.6% |
| Wells over the level / wells judged | 2 of 346 |
| Median | 6.72 mg/L |
| Years sampled | 1956–2025 |
| Wells | 346 |
| Test results | 539 |
| Wells left out | 1 |
| Sources | MNDNR_AGW (185), USGS (100), MNPCA_AGW (61) |