Miami-Dade County, FL
These figures come from wells tested in Miami-Dade County, FL, not from any one well.
- Iron is common in wells in Miami-Dade County, FL (74 of 131 tested wells were over that level), so it's worth testing for.
- Sulfate is common in wells in Miami-Dade County, FL (88 of 771 tested wells were over that level), so it's worth testing for.
- Manganese is not common in wells in Miami-Dade County, FL (8 of 118 tested wells were over). Only a test tells you about your own well.
- Wells in Miami-Dade County, FL are typically very hard (754 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)
- sulfate (common in wells here)
- 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. Florida'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 | 56% |
| Wells over the level / wells judged | 74 of 131 |
| Median | 0.409 mg/L |
| Years sampled | 1920–2024 |
| Wells | 131 |
| Test results | 1,769 |
| Wells left out | 34 |
| Sources | USGS (581), 21FLGW_WQX (43), 21FLSFWM (6) |
Manganese Recent
| Level it's compared with | 0.05 mg/L |
|---|---|
| Share of wells over the level | 6.8% |
| Wells over the level / wells judged | 8 of 118 |
| Median | 0.0064225 mg/L |
| Years sampled | 1948–2024 |
| Wells | 118 |
| Test results | 1,319 |
| Wells left out | 20 |
| Sources | USGS (438), 21FLGW_WQX (43) |
Hardness Recent
| Level it's compared with | none; hardness is shown in bands |
|---|---|
| Share of wells very hard | 95% |
| Median | 260 mg/L as CaCO₃ |
| Years sampled | 1907–2025 |
| Wells | 754 |
| Test results | 2,119 |
| Wells left out | 34 |
| Sources | USGS (711), 21FLGW_WQX (43) |
Sulfate Recent
| Level it's compared with | 250 mg/L |
|---|---|
| Share of wells over the level | 11% |
| Wells over the level / wells judged | 88 of 771 |
| Median | 22.5 mg/L |
| Years sampled | 1907–2025 |
| Wells | 771 |
| Test results | 2,182 |
| Wells left out | 4 |
| Sources | USGS (728), 21FLGW_WQX (43) |