Health problems are rare in tested Polk County wells.
All 6 health checks came back rare here.
From 187 wells tested in Polk County since 2000; your own well needs its own test. How to read this
Not charted, because fewer than 10 wells were tested: radon (9).
Rare: under 5%Worth checking: 5 to 15%Widespread: 15%+
Lab results: Water Quality Portal (USGS and EPA)
Who drinks from a well here
About 1 in 14 people 50,232 people
Nobody else tests these wells. Only you do.
People on wells: EPA researchers' 2020 estimate
Radon risk (a gas from rock)
Possible here. A home air test is inexpensive.
Radon zones: EPA map
Here's how Polk County compares with Florida and the counties around it.
Each result puts Polk County next to the 10 counties that border it, on the chart's 0 to 50% scale.
All 6 health checks are rare in Polk County.
Nitrate4 of 95 wells over
Too few tested to show: Hardee.
Manganese4 of 177 wells over
Arsenic1 of 84 wells over
Lead0 of 77 wells over
Fluoride0 of 177 wells over
Uranium0 of 15 wells over
Too few tested to show: Hardee, Highlands, Lake, Manatee, Okeechobee, Orange, Osceola, Sumter.
Too few Polk County wells were tested for this one.
Radon in water9 wells tested
Coliform bacteria turned up in 45 of 71 tested Polk County wells, so test for it every year.
Coliform bacteria45 of 71 wells had it
Most of Florida's bacteria results come from shallow monitoring-network wells, so they aren't a guide to household wells.
E. coli6 of 43 wells had it
Too few tested to show: Hardee.
E. coli means human or animal waste is getting in, so if a test of your Polk County well finds it, boil drinking water until the well is fixed.
Iron reached staining levels in 51 of 186 tested wells, and it isn't a health risk.
Iron stains51 of 186 wells had it
About 6 in 10 of the 187 wells tested in Polk County have a test from 2020 or later.
With 117 wells tested since 2020, age matters less here than who did the testing and why.
Most Polk County wells in these records were tested for research or because someone suspected a problem, which can push the shares above what a typical home well would show (how we read the numbers).
One mail-in lab test covers the 3 things to check in Polk County.
- Bacteria
- Nitrate
- Arsenic
What Florida offers well owners
- Free testingSome county health departments may test for certain toxic substances free of charge. See the program
- Certified labsFlorida's list of certified labs
- Well recordsWe didn't find an online search.
- New wellsNo statewide rule. We didn't find a local rule for Polk County, so ask its health department.
Here's what we know about radon and PFAS in Polk County.
Polk County is in the EPA's middle radon zone. An indoor air test is cheap and tells you whether to look at your water. Radon guide
Between 2023 and 2025 the EPA had 21 town water systems in Polk County test for PFAS. 5 of them had at least one test above 4 ng/L, the new EPA limit for PFOA and PFOS. The highest single result was 13 ng/L of PFOS. No well in Polk County has public PFAS results, so the town systems are the best clue to what's in the groundwater nearby. PFAS guide
Radon zones: EPA Map of Radon Zones. PFAS: EPA tests of town water systems, 2023 to 2025
Questions people ask about well water in Polk County
Is well water in Polk County safe to drink?
Most tested wells in Polk County came in under the limits. Of 6 health checks with enough tests, nitrate came closest, at 4 of 95 wells over. Every well is different, so test yours for bacteria, nitrate and arsenic.
Can I get my well tested for free in Polk County?
Some county health departments may test for certain toxic substances free of charge. If not, use a lab Florida has certified for drinking water. Ask for bacteria, nitrate and arsenic, the tests that matter most in Polk County.
How does Polk County compare with the counties around it?
For nitrate, the share of tested wells over the limit: Polk County, at 4%, had a higher share than all 9 neighboring counties with data. Groundwater doesn't stop at county lines, so Hillsborough's 3% is worth knowing about if you live near it.
How often should I test my well in Polk County?
In Polk County, 45 of 71 tested wells had coliform bacteria, so the CDC's advice matters here: test for bacteria and nitrate every year, and right away after a flood, a repair, or any change in taste or smell.
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Where the Polk County numbers come from
- People on wells: 50,232 in Polk County, from EPA estimates built on the 2020 Census (Murray et al.).
- Lab tests: 5,167 well water samples from 187 wells in the Water Quality Portal, run by the USGS and EPA, 2000 to 2026.
- Neighboring counties: the 10 counties that share a border with Polk County, from the Census Bureau's county adjacency file.
- PFAS: EPA tests of 21 town water systems in Polk County under the Fifth Unregulated Contaminant Monitoring Rule, 2023 to 2025.
- Radon: Polk County is zone 2 on the EPA Map of Radon Zones.
- State programs and links: Department of Health, checked November 1, 2026.