Well water in Hillsborough County, Florida
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Testing recommended
tested well samples in Hillsborough County exceeded the EPA limit for arsenic (10 ug/L), based on public data from USGS Water Quality Portal.
14,776 test results across 12 contaminants from at least 651 wells, 1923 to 2025; sodium has the most at 3,317. Data refreshed September 15, 2026.
Compiled by Nick at Well Water Nerd from public records. How these pages are built
An estimated 126,523 people in Hillsborough County get their drinking water from a private well, per USGS 2015 county water use. That is about 9% of residents.
Separately, the USGS national arsenic model estimates that <1% of the 126,523 people on private wells in Hillsborough County draw water above 10 ug/L, from geology and well depth rather than local tests.
What individual samples found
Each row summarizes every public sample for that contaminant inside Hillsborough County. Above limit means above the EPA maximum contaminant level; where EPA has no enforceable limit, the row shows a health guideline or nuisance level instead.
| Contaminant | Above limit | Samples | Detected | Median | Highest | Limit |
|---|---|---|---|---|---|---|
| Arsenic 1969 to 2024 | 845 | 79% | 1 | 32 | 10 ug/L EPA limit | |
| Lead 1969 to 2024 | 866 | 81% | 0 | 1,000 | 15 ug/L EPA limit | |
| Radium (226 + 228) 1974 to 2012 | 124 | 86% | 0.525 | 6 | 5 pCi/L EPA limit | |
| Nitrate 1930 to 2023 | 1,853 | 75% | 0.01 | 1,200 | 10 mg/L EPA limit | |
| Fluoride 1953 to 2025 | 2,057 | 92% | 0.29 | 9 | 4 mg/L EPA limit | |
| Copper 1969 to 2024 | 814 | 83% | 0 | 1.3 | 1.3 mg/L EPA limit | |
| Uranium 1979 to 2012 | 141 | 78% | 0.07 | 7.13 | 30 ug/L EPA limit | |
| Sodium 1953 to 2025 | no limit | 3,317 | 100% | 9.8 | 18,000 | 20 mg/L health guideline |
| Iron 1923 to 2025 | no limit | 2,835 | 98% | 206 | 121,000 | 300 ug/L nuisance level |
| Manganese 1942 to 2025 | no limit | 1,843 | 97% | 5.12 | 939 | 300 ug/L health guideline |
| Radon 1995 to 2012 | no limit | 75 | 100% | 880 | 4,900 | 2,000 pCi/L health guideline |
Sampled fewer than 10 times, too few to summarize: Chloride (6).
Over time
Share of samples above the limit by period. A cell needs ten samples to show; a comparison needs twenty in each period. Later periods sample fewer wells, and often the ones already known to have a problem.
| Contaminant | before 2000 | 2000s | 2010s | 2020s |
|---|---|---|---|---|
| Fluoride | <1%746 samples | 0%146 samples | 0%431 samples | 0%734 samples |
| Nitrate | 1%1,400 samples | 6%351 samples | 5%86 samples | 0%16 samples |
| Lead | 7%668 samples | 3%104 samples | 0%59 samples | 3%35 samples |
| Arsenic | 7%647 samples | 8%104 samples | 0%59 samples | 3%35 samples |
| Copper | 0%621 samples | 0%99 samples | 0%59 samples | 0%35 samples |
| Uranium | 0%47 samples | 0%68 samples | 0%26 samples | n/a |
Fluoride, nitrate, lead, arsenic, copper, uranium have held within a few points between the two most recent periods with enough samples.
Closer than the county
See the sampled wells near your address
The same records, drawn around one point: which wells within a few miles were sampled and what they found, how deep the wells next to you were drilled, and any leaking tank or cleanup site within a mile.
Check my addressWhat this means
The contaminants most often above their limit here are arsenic (6% of 845 samples), lead (6% of 866 samples), and radium (226 + 228) (2% of 124 samples). A well next door can differ sharply from yours because bedrock fractures, well depth and plumbing all matter, so these rates describe the area, not your tap.
Iron, Manganese, and Chloride are widespread in local groundwater. They are mainly a staining and taste problem, but high manganese also carries a health advisory for infants.
What to test for in Hillsborough County
- 1Arsenic6% of 845 local samples were above the limit.
- 2Lead6% of 866 local samples were above the limit.
- 3Radium (226 + 228)2% of 124 local samples were above the limit.
- 4Nitrate2% of 1,853 local samples were above the limit.
- 5Fluoride<1% of 2,057 local samples were above the limit.
- 6Coliform bacteriaRecommended for every private well, every year.
- 7RadonMedian local reading is 880 pCi/L.
- 8Volatile organic compounds (VOCs)3,214 leaking underground storage tank sites on record locally.
- 9Metals panel19 hazardous waste sites on record locally.
Test your Hillsborough County well for arsenic, lead and radium (226 + 228)
Certified lab analysis of your own tap water, bottles and prepaid return shipping included. The Essential well panel covers arsenic, uranium, nitrate, lead, copper, manganese, iron, sodium and bacteria; radon and PFAS are add-ons.
Order the Tap Score well water test kit, from $209Already tested? Upload the report
Just want bacteria checked first? Tap Score coliform and E. coli test, $99. Coliform and E. coli are the tests every well needs every year.
Want a quick look before paying for a lab? Home well water test strips on Amazon check hardness, iron, pH and nitrate in minutes. They are a screen, not a result: arsenic, bacteria, uranium and PFAS need a certified lab.
Affiliate links: the merchant pays us a commission and the price is the same for you. It does not change what the data above says. As an Amazon Associate we earn from qualifying purchases.
Where to get a well tested in Florida: certified labs, state programs and prices.
Already have results back? Get your lab report read against the Hillsborough County numbers, $29. Every line explained, ranked by what matters, with the fix for each.
Official help in Florida
Two places to start that are not selling anything: the state program that answers private well questions, and its list of labs certified to run drinking water tests. A certified lab is the difference between a result you can act on and a number.
- Private Well Water Testing, Florida Department of Health
- NELAP Certified Laboratory Search, Florida DEP
Contamination sources on record in Hillsborough County
FDEP records 3,214 leaking underground storage tank sites and 19 hazardous waste sites in Hillsborough County, among 4,158 regulated sites in total. Groundwater does not follow property lines, so a well within a few hundred feet of one of these is worth testing for what that site could release.
- 3,214
- leaking underground storage tank sitesGasoline and heating oil that leaked from tanks move through groundwater as benzene, MTBE and other volatile organic compounds.
- 19
- hazardous waste sitesSolvents, degreasers and metals from industrial sites can travel far in fractured bedrock.
- 925
- other remediation projects
Treatment that fits the local profile
Arsenic
Point-of-use reverse osmosis; Adsorptive media (iron-based) whole-house; Anion exchange
Lead
Point-of-use reverse osmosis; Certified lead-removal carbon filter; Neutralizing filter to raise pH and stop leaching
Radium (226 + 228)
Water softener (cation exchange); Point-of-use reverse osmosis
Nitrate
Point-of-use reverse osmosis; Anion exchange; Distillation
Fluoride
Point-of-use reverse osmosis; Activated alumina; Distillation
Systems we would look at first
Some links below are affiliate links. If you buy through one, the merchant pays us a commission at no extra cost to you. It does not change which products we list or what the data says.
For arsenic
Under-sink reverse osmosis system
under-sink or countertop, about $300
Look for NSF/ANSI 58 certification listing the contaminant you need removed.
For arsenic
Whole-house arsenic and uranium filter
whole-house, at the point of entry, about $2,500
Adsorptive iron-based media; sized to your well yield.
For arsenic
Aquasana SmartFlow reverse osmosis
under-sink or countertop, about $225
Certified to NSF/ANSI 58 and 53 to reduce arsenic (96%, pentavalent), fluoride (90%), lead (99%), nitrate, nitrite and PFOA/PFOS at the kitchen tap, with a remineralizer.
For lead
Aquasana Claryum 3-Stage under-sink filter
under-sink or countertop, about $175
Certified to NSF/ANSI 53 to reduce 99% of lead and 99.7% of PFOA and PFOS at the tap. Not a fix for arsenic, nitrate or bacteria.
For lead
Acid neutralizing filter
whole-house, at the point of entry, about $1,200
Raises pH so plumbing stops leaching lead and copper.
For iron
Iron and manganese oxidizing filter
whole-house, at the point of entry, about $1,800
Air-injection or greensand media; fixes staining at the source.
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Common questions
Is there arsenic in well water in Hillsborough County?
Arsenic was detected in 79% of 845 public well samples in Hillsborough County, and 6% were above the EPA limit of 10 ug/L. Arsenic has no taste or smell; a lab test is the only way to know your level.
How high is radon in well water in Hillsborough County?
The median radon level across 75 public samples in Hillsborough County was 880 pCi/L, with a high of 4,900 pCi/L. New Hampshire recommends treatment above 2,000 pCi/L.
How often should I test a private well in Hillsborough County?
Test for bacteria and nitrate every year. Test once for arsenic, uranium, radon, fluoride, manganese and PFAS, then again every three to five years or after any change in taste, color, or plumbing.
Counties near Hillsborough County
Closest first. Groundwater does not stop at a line on a map, so the next county over is a fair second opinion.
Want the numbers themselves? Download the Florida dataset as CSV, every county and town, with the sources named.
Sources
- USGS Water Quality Portal: 14,776 samples in Hillsborough County. Data from the Water Quality Portal, a service of USGS, EPA and USDA; groundwater samples collected by USGS and cooperators. Retrieved September 3, 2026.
- USGS national arsenic model (Ayotte 2017): estimated share of 126,523 people on private wells in Hillsborough County above 10 ug/L of arsenic, from geology, well depth and land use. County estimates of domestic well users with arsenic above 10 ug/L from the USGS national logistic regression model (Ayotte, Medalie and Qi, 2017), with private well population from the USGS 2015 county water-use compilation (Dieter and others, 2018). Retrieved September 15, 2026.
- FDEP regulated sites: 4,158 regulated sites located in Hillsborough County. Petroleum contamination discharges and cleanup sites from the Florida Department of Environmental Protection. Retrieved September 17, 2026.
Non-detects count as samples and are treated as zero when computing medians. Exactly at the limit counts as not above it. A sample belongs to the town containing the well's reported coordinates.