Washington County, MN
These figures come from wells tested in Washington County, MN, not from any one well.
- Iron is common in wells in Washington County, MN (54 of 205 tested wells were over that level), so it's worth testing for.
- Manganese is common in wells in Washington County, MN (40 of 140 tested wells were over that level), so it's worth testing for.
- Sulfate is not common in wells in Washington County, MN (0 of 313 tested wells were over). Only a test tells you about your own well.
- Wells in Washington County, MN are typically very hard (311 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 | 26% |
| Wells over the level / wells judged | 54 of 205 |
| Median | < DL mg/L |
| Years sampled | 1957–2025 |
| Wells | 205 |
| Test results | 1,001 |
| Wells left out | 6 |
| Sources | MNPCA_AGW (209), MNDNR_AGW (90), USGS (64) |
More than half the wells had results below the lab's detection limit, so the median is reported as below that limit.
Manganese Recent
| Level it's compared with | 0.05 mg/L |
|---|---|
| Share of wells over the level | 29% |
| Wells over the level / wells judged | 40 of 140 |
| Median | 0.005 mg/L |
| Years sampled | 1957–2025 |
| Wells | 140 |
| Test results | 847 |
| Wells left out | 6 |
| Sources | MNPCA_AGW (150), MNDNR_AGW (90), USGS (56) |
Hardness Recent
| Level it's compared with | none; hardness is shown in bands |
|---|---|
| Share of wells very hard | 91% |
| Median | 244 mg/L as CaCO₃ |
| Years sampled | 1957–2025 |
| Wells | 311 |
| Test results | 838 |
| Wells left out | 6 |
| Sources | MNPCA_AGW (146), MNDNR_AGW (89), USGS (76) |
Sulfate Recent
| Level it's compared with | 250 mg/L |
|---|---|
| Share of wells over the level | 0.0% |
| Wells over the level / wells judged | 0 of 313 |
| Median | 8.14 mg/L |
| Years sampled | 1957–2025 |
| Wells | 313 |
| Test results | 878 |
| Wells left out | 6 |
| Sources | MNPCA_AGW (146), MNDNR_AGW (90), USGS (77) |