Hillsborough County, FL
These figures come from wells tested in Hillsborough County, FL, not from any one well.
- Iron is common in wells in Hillsborough County, FL (63 of 133 tested wells were over that level), so it's worth testing for.
- Manganese is common in wells in Hillsborough County, FL (12 of 117 tested wells were over that level), so it's worth testing for.
- Sulfate is common in wells in Hillsborough County, FL (119 of 661 tested wells were over that level), so it's worth testing for.
- Wells in Hillsborough County, FL are typically very hard (648 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. 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 | 47% |
| Wells over the level / wells judged | 63 of 133 |
| Median | 0.2235 mg/L |
| Years sampled | 1923–2025 |
| Wells | 133 |
| Test results | 1,510 |
| Wells left out | 111 |
| Sources | USGS (317), 21FLGW_WQX (28), 21FLSWFD_WQX (20), 21FLTBW_WQX (5) |
Manganese Recent
| Level it's compared with | 0.05 mg/L |
|---|---|
| Share of wells over the level | 10% |
| Wells over the level / wells judged | 12 of 117 |
| Median | 0.008125 mg/L |
| Years sampled | 1942–2025 |
| Wells | 117 |
| Test results | 881 |
| Wells left out | 66 |
| Sources | USGS (187), 21FLGW_WQX (28), 21FLSWFD_WQX (20), 21FLTBW_WQX (5) |
Hardness Recent
| Level it's compared with | none; hardness is shown in bands |
|---|---|
| Share of wells very hard | 62% |
| Median | 205 mg/L as CaCO₃ |
| Years sampled | 1923–2025 |
| Wells | 648 |
| Test results | 2,432 |
| Wells left out | 143 |
| Sources | USGS (595), 21FLGW_WQX (28), 21FLSWFD_WQX (20), 21FLTBW_WQX (5) |
Sulfate Recent
| Level it's compared with | 250 mg/L |
|---|---|
| Share of wells over the level | 18% |
| Wells over the level / wells judged | 119 of 661 |
| Median | 29.4 mg/L |
| Years sampled | 1923–2025 |
| Wells | 661 |
| Test results | 2,547 |
| Wells left out | 84 |
| Sources | USGS (604), 21FLGW_WQX (28), 21FLSWFD_WQX (20), 21FLTBW_WQX (9) |