Health problems are rare in tested Lake County wells.

All 5 health checks came back rare here.

From 112 wells tested in Lake County since 2000; your own well needs its own test. How to read this

Tested wells over the limit LakeFlorida

Arsenic1%1 of 107 Lead1%1 of 107 Nitrate0%0 of 88 Fluoride0%0 of 46 Manganese0%0 of 109

GermsTest every year, whatever the chart says

Coliform bacteria44%18 of 41 E. coli5%1 of 21

StainsNot a health risk

Iron stains40%44 of 109

Not charted, because fewer than 10 wells were tested: uranium (3), radon (3).

Rare: under 5%Worth checking: 5 to 15%Widespread: 15%+

Lab results: Water Quality Portal (USGS and EPA)

Show bacteria and iron

Who drinks from a well here

1 in 6 people 68,936 people

Nobody else tests these wells. Only you do.

People on wells: EPA researchers' 2020 estimate

Radon risk (a gas from rock)

LowMiddleHigh

Less likely, but the EPA still says test your air.

Radon zones: EPA map

Here's how Lake County compares with Florida and the counties around it.

Each result puts Lake County next to the 7 counties that border it, on the chart's 0 to 50% scale.

All 5 health checks are rare in Lake County.

Arsenic1 of 107 wells over

1 of 107 wells tested here from 2002 to 2025 was over the EPA limit of 10 µg/L, against about 1 in 9 across Florida. That's a smaller share than in 41 of the 63 other Florida counties with 10 or more tested wells.

Lake and its neighbors

Orange3%

Seminole2%

Volusia2%

Polk1%

Lake1%

Marion0%

Osceola0%

Sumter0%

Arsenic guide

Lead1 of 107 wells over

1 of 107 wells tested here from 2002 to 2025 was over the EPA action level of 15 µg/L, against about 1 in 9 across Florida. That's a smaller share than in 33 of the 63 other Florida counties with 10 or more tested wells.

Lake and its neighbors

Sumter7%

Volusia2%

Seminole2%

Lake1%

Marion1%

Orange0%

Osceola0%

Polk0%

Lead guide

Nitrate0 of 88 wells over

None of the 88 wells tested here from 2000 to 2025 were over the EPA limit of 10 mg/L, against about 1 in 32 across Florida. At least half the results were too low for the lab to measure, and the top 1 in 10 were 6.0 mg/L or more. Lake County had none, while 25 of the 59 other Florida counties with 10 or more tested wells had at least one.

Lake and its neighbors

Polk4%

Marion3%

Lake0%

Orange0%

Osceola0%

Seminole0%

Sumter0%

Volusia0%

Nitrate guide

Fluoride0 of 46 wells over

None of the 46 wells tested here from 2001 to 2025 were over the EPA limit of 4 mg/L, against under 1 in 50 across Florida. At least half the results were too low for the lab to measure, and the top 1 in 10 were 0.18 mg/L or more. Lake County had none, while 16 of the 63 other Florida counties with 10 or more tested wells had at least one.

Lake and its neighbors

Lake0%

Marion0%

Orange0%

Osceola0%

Polk0%

Seminole0%

Sumter0%

Volusia0%

Manganese0 of 109 wells over

None of the 109 wells tested here from 2002 to 2025 were over the EPA health advisory of 0.3 mg/L, against under 1 in 100 across Florida. At least half the results were too low for the lab to measure, and the top 1 in 10 were 0.023 mg/L or more. Lake County had none, while 15 of the 63 other Florida counties with 10 or more tested wells had at least one.

Lake and its neighbors

Marion4%

Polk2%

Lake0%

Orange0%

Osceola0%

Seminole0%

Sumter0%

Volusia0%

Manganese guide

Too few Lake County wells were tested for these 2.

Uranium3 wells tested

Only 3 wells here were tested from 2002 to 2015, too few to say how common it is. Across Florida it's under 1 in 100.

Uranium guide

Radon in water3 wells tested

Only 3 wells here were tested from 2002 to 2015, too few to say how common it is. Across Florida it's about 1 in 45.

Radon guide

Coliform bacteria turned up in 18 of 41 tested Lake County wells, so test for it every year.

Coliform bacteria18 of 41 wells had it

About 4 in 10 wells tested here from 2015 to 2025 had coliform bacteria, against about 5 in 10 across Florida.

Lake and its neighbors

Polk63%

Marion58%

Orange50%

Sumter50%

Volusia49%

Osceola47%

Lake44%

Seminole35%

Most of Florida's bacteria results come from shallow monitoring-network wells, so they aren't a guide to household wells.

Bacteria guide

E. coli1 of 21 wells had it

1 of 21 wells tested here from 2015 to 2025 had E. coli, against about 1 in 12 across Florida.

Lake and its neighbors

Seminole27%

Polk14%

Marion7%

Lake5%

Orange0%

Osceola0%

Sumter0%

Volusia0%

E. coli means human or animal waste is getting in, so if a test of your Lake County well finds it, boil drinking water until the well is fixed.

Bacteria guide

Iron reached staining levels in 44 of 109 tested wells, and it isn't a health risk.

Iron stains44 of 109 wells had it

About 4 in 10 wells tested here from 2000 to 2025 had enough iron to stain (0.3 mg/L), against about 4 in 10 across Florida.

Lake and its neighbors

Sumter52%

Volusia49%

Seminole46%

Lake40%

Osceola35%

Orange32%

Polk27%

Marion20%

Iron guide

About 8 in 10 of the 112 wells tested in Lake County have a test from 2020 or later.

8 wells had a test in the 2000s, 79 in the 2010s and 86 since 2020.

With 86 wells tested since 2020, age matters less here than who did the testing and why.

Most Lake 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 Lake 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 Lake County, so ask its health department.

Here's what we know about radon and PFAS in Lake County.

Lake County is in the EPA's lowest radon zone, so radon from well water is unlikely to be a problem. Radon guide

Between 2023 and 2025 the EPA had 19 town water systems in Lake County test for PFAS. 11 of them had at least one test above 4 ng/L, the new EPA limit for PFOA and PFOS. The highest single result was 32 ng/L of PFOS. No well in Lake 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

Next door to Lake County

Marion Volusia Orange Seminole Polk

Elsewhere in Florida

Duval Brevard Hillsborough

All of Florida

Questions people ask about well water in Lake County

Is well water in Lake County safe to drink?

Most tested wells in Lake County came in under the limits. Of 5 health checks with enough tests, arsenic came closest, at 1 of 107 wells over. Every well is different, so test yours for bacteria, nitrate and arsenic.

Can I get my well tested for free in Lake 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 Lake County.

How does Lake County compare with the counties around it?

For arsenic, the share of tested wells over the limit: 4 of the 7 neighboring counties with data had a higher share than Lake County, at 1%. Orange had the most, at 3%. Groundwater doesn't stop at county lines, so Orange's 3% is worth knowing about if you live near it.

How often should I test my well in Lake County?

In Lake County, 18 of 41 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.

By the Tested Water teamData from the USGS, EPA and Department of HealthUpdated November 8, 2026

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Where the Lake County numbers come from

People on wells: 68,936 in Lake County, from EPA estimates built on the 2020 Census (Murray et al.).
Lab tests: 1,776 well water samples from 112 wells in the Water Quality Portal, run by the USGS and EPA, 2000 to 2025.
Neighboring counties: the 7 counties that share a border with Lake County, from the Census Bureau's county adjacency file.
PFAS: EPA tests of 19 town water systems in Lake County under the Fifth Unregulated Contaminant Monitoring Rule, 2023 to 2025.
Radon: Lake County is zone 3 on the EPA Map of Radon Zones.
State programs and links: Department of Health, checked November 1, 2026.

Download this county's data (CSV)How we read these numbers Report an error