Health problems are rare in tested Marion County wells.

All 5 health checks came back rare here.

From 175 wells tested in Marion County since 2001; your own well needs its own test. How to read this

Tested wells over the limit MarionFlorida

Manganese4%7 of 173 Nitrate3%5 of 161 Lead1%1 of 108 Arsenic0%0 of 92 Fluoride0%0 of 126

GermsTest every year, whatever the chart says

Coliform bacteria58%25 of 43 E. coli7%2 of 30

StainsNot a health risk

Iron stains20%34 of 173

Not charted, because fewer than 10 wells were tested: uranium (6), radon (6).

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 3 people 137,486 people

Nobody else tests these wells. Only you do.

People on wells: EPA researchers' 2020 estimate

How deep wells go here

Middle depth: some shelter from the surface, not complete.

Well depths: US Groundwater Well Database

Radon risk (a gas from rock)

LowMiddleHigh

Possible here. A home air test is inexpensive.

Radon zones: EPA map

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

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

All 5 health checks are rare in Marion County.

Manganese7 of 173 wells over

About 1 in 25 wells tested here from 2001 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 0.032 mg/L or more. That's the highest share among the 64 Florida counties with 10 or more tested wells.

Marion and its neighbors

Marion4%

Alachua2%

Citrus1%

Lake0%

Levy0%

Putnam0%

Sumter0%

Volusia0%

Manganese guide

Nitrate5 of 161 wells over

About 1 in 32 wells tested here from 2001 to 2026 were over the EPA limit of 10 mg/L, against about 1 in 32 across Florida. Half the results were under 0.77 mg/L, and the top 1 in 10 were 3.0 mg/L or more. That's a bigger share than in 43 of the 59 other Florida counties with 10 or more tested wells.

Marion and its neighbors

Alachua12%

Levy6%

Marion3%

Citrus1%

Lake0%

Putnam0%

Sumter0%

Volusia0%

Nitrate guide

Lead1 of 108 wells over

1 of 108 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 34 of the 63 other Florida counties with 10 or more tested wells.

Marion and its neighbors

Levy40%

Alachua16%

Sumter7%

Volusia2%

Lake1%

Marion1%

Citrus0%

Putnam0%

Lead guide

Arsenic0 of 92 wells over

None of the 92 wells tested here from 2002 to 2025 were over the EPA limit of 10 µg/L, against about 1 in 9 across Florida. Marion County had none, while 43 of the 63 other Florida counties with 10 or more tested wells had at least one.

Marion and its neighbors

Levy31%

Alachua15%

Citrus6%

Putnam2%

Volusia2%

Lake1%

Marion0%

Sumter0%

Arsenic guide

Fluoride0 of 126 wells over

None of the 126 wells tested here from 2001 to 2026 were over the EPA limit of 4 mg/L, against under 1 in 50 across Florida. Half the results were under 0.1 mg/L, and the top 1 in 10 were 0.34 mg/L or more. Marion County had none, while 16 of the 63 other Florida counties with 10 or more tested wells had at least one.

Marion and its neighbors

Alachua7%

Levy3%

Citrus0%

Lake0%

Marion0%

Putnam0%

Sumter0%

Volusia0%

Too few Marion County wells were tested for these 2.

Uranium6 wells tested

Only 6 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 water6 wells tested

Only 6 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 25 of 43 tested Marion County wells, so test for it every year.

Coliform bacteria25 of 43 wells had it

About 6 in 10 wells tested here from 2002 to 2026 had coliform bacteria, against about 5 in 10 across Florida.

Marion and its neighbors

Citrus59%

Marion58%

Sumter50%

Volusia49%

Levy45%

Alachua44%

Lake44%

Putnam44%

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

Bacteria guide

E. coli2 of 30 wells had it

2 of 30 wells tested here from 2002 to 2026 had E. coli, against about 1 in 12 across Florida.

Marion and its neighbors

Alachua9%

Marion7%

Lake5%

Levy0%

Sumter0%

Volusia0%

Too few tested to show: Citrus, Putnam.

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

Bacteria guide

Iron reached staining levels in 34 of 173 tested wells, and it isn't a health risk.

Iron stains34 of 173 wells had it

About 2 in 10 wells tested here from 2001 to 2025 had enough iron to stain (0.3 mg/L), against about 4 in 10 across Florida.

Marion and its neighbors

Sumter52%

Putnam51%

Volusia49%

Levy47%

Lake40%

Alachua37%

Citrus36%

Marion20%

Iron guide

About 6 in 10 of the 175 wells tested in Marion County have a test from 2020 or later.

51 wells had a test in the 2000s, 99 in the 2010s and 102 since 2020.

With 102 wells tested since 2020, age matters less here than who did the testing and why.

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

Half the household wells here are shallower than 80 feet.

That comes from 31 household wells in Florida's drilling records. Most wells of every kind here are 50 to 115 feet deep. Wells as deep as Marion County's are usually better protected from fertilizer and bacteria at the surface, but they can pick up more of what's in the rock, like arsenic and uranium. Typical household wells here are shallower than in 25 of the 29 other Florida counties with enough drilling records.

How to find your own well's depth

Well depths: US Groundwater Well Database

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

Marion 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 9 town water systems in Marion County test for PFAS. 7 of them had at least one test above 4 ng/L, the new EPA limit for PFOA and PFOS. The highest single result was 39 ng/L of PFOS. No well in Marion 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 Marion County

Volusia Lake Citrus Putnam Alachua

Elsewhere in Florida

Duval Brevard Hillsborough

All of Florida

Questions people ask about well water in Marion County

Is well water in Marion County safe to drink?

Most tested wells in Marion County came in under the limits. Of 5 health checks with enough tests, manganese came closest, at 7 of 173 wells over. Every well is different, so test yours for bacteria, nitrate and arsenic.

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

How deep are wells in Marion County?

Half the household wells here are shallower than 80 feet. Typical household wells here are shallower than in 25 of the 29 other Florida counties with enough drilling records.

How does Marion County compare with the counties around it?

For manganese, the share of tested wells over the limit: Marion County, at 4%, had a higher share than all 7 neighboring counties with data. Groundwater doesn't stop at county lines, so Alachua's 2% is worth knowing about if you live near it.

How often should I test my well in Marion County?

In Marion County, 25 of 43 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 Marion County numbers come from

People on wells: 137,486 in Marion County, from EPA estimates built on the 2020 Census (Murray et al.).
Lab tests: 3,895 well water samples from 175 wells in the Water Quality Portal, run by the USGS and EPA, 2001 to 2026.
Well depths: 31 Florida drilling records for Marion County, gathered in the US Groundwater Well Database (Lin and others, 2024).
Neighboring counties: the 7 counties that share a border with Marion County, from the Census Bureau's county adjacency file.
PFAS: EPA tests of 9 town water systems in Marion County under the Fifth Unregulated Contaminant Monitoring Rule, 2023 to 2025.
Radon: Marion County is zone 2 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