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Nitrate in Florida well water, by county

By the Tested Water teamLab data from the USGS and EPA Water Quality Portal, 2000 to 2026Updated November 8, 2026

Nitrate is widespread, over the limit in 15% or more of tested wells, in 2 of the 60 Florida counties with 10 or more tested wells. A county's share tells you how likely a problem is nearby. Only a test of your own well tells you what's in it.

Find a nitrate test See every county

How Florida compares with the rest of the country

Across Florida, about 1 in 32 tested wells had nitrate over the EPA limit of 10 mg/L (111 of 3,501). Across all tested wells in the US it's about 1 in 12. That's less often than in the country as a whole. Counties still differ, so check yours below.

Why it matters: It's dangerous for babies under 6 months, because it keeps their blood from carrying enough oxygen.

Nitrate soaks down into groundwater from fertilizer, manure and septic systems.

Nitrate in tested wells, county by county

Share of each county's tested wells with at least one result over the EPA limit of 10 mg/L. Counties need 10 or more tested wells to be listed. Widespread means 15% or more, worth checking 5 to 15%, rare under 5%.

CountyWells testedWells over the limitLevel
Duval County 78
23% 18 of 78
 Widespread
Gilchrist County 99
17% 17 of 99
 Widespread
Alachua County 105
12% 13 of 105
 Worth checking
Pinellas County 11
9% 1 of 11
 Worth checking
Union County 23
9% 2 of 23
 Worth checking
Bradford County 26
8% 2 of 26
 Worth checking
Suwannee County 132
8% 10 of 132
 Worth checking
Leon County 43
7% 3 of 43
 Worth checking
Levy County 167
6% 10 of 167
 Worth checking
Lafayette County 71
6% 4 of 71
 Worth checking
Hamilton County 40
5% 2 of 40
 Worth checking
Baker County 21
5% 1 of 21
 Rare
Polk County 95
4% 4 of 95
 Rare
Indian River County 28
4% 1 of 28
 Rare
Hillsborough County 121
3% 4 of 121
 Rare
Hendry County 31
3% 1 of 31
 Rare
Marion County 161
3% 5 of 161
 Rare
Pasco County 108
3% 3 of 108
 Rare
Wakulla County 36
3% 1 of 36
 Rare
Dixie County 52
2% 1 of 52
 Rare
Highlands County 54
2% 1 of 54
 Rare
Jackson County 59
2% 1 of 59
 Rare
Collier County 258
2% 4 of 258
 Rare
Taylor County 66
2% 1 of 66
 Rare
Citrus County 78
1% 1 of 78
 Rare
Columbia County 138
0% 0 of 138
 Rare
Volusia County 114
0% 0 of 114
 Rare
Miami-Dade County 103
0% 0 of 103
 Rare
Lake County 88
0% 0 of 88
 Rare
Palm Beach County 83
0% 0 of 83
 Rare
Madison County 76
0% 0 of 76
 Rare
Orange County 71
0% 0 of 71
 Rare
Seminole County 61
0% 0 of 61
 Rare
Lee County 52
0% 0 of 52
 Rare
Clay County 48
0% 0 of 48
 Rare
St. Johns County 46
0% 0 of 46
 Rare
Putnam County 45
0% 0 of 45
 Rare
Broward County 43
0% 0 of 43
 Rare
Brevard County 40
0% 0 of 40
 Rare
Hernando County 40
0% 0 of 40
 Rare
Sumter County 40
0% 0 of 40
 Rare
Jefferson County 31
0% 0 of 31
 Rare
Flagler County 29
0% 0 of 29
 Rare
Martin County 28
0% 0 of 28
 Rare
Nassau County 28
0% 0 of 28
 Rare
Osceola County 27
0% 0 of 27
 Rare
Bay County 26
0% 0 of 26
 Rare
Okeechobee County 25
0% 0 of 25
 Rare
Santa Rosa County 25
0% 0 of 25
 Rare
Walton County 24
0% 0 of 24
 Rare
Manatee County 23
0% 0 of 23
 Rare
Escambia County 19
0% 0 of 19
 Rare
St. Lucie County 19
0% 0 of 19
 Rare
Gulf County 18
0% 0 of 18
 Rare
Okaloosa County 16
0% 0 of 16
 Rare
Charlotte County 15
0% 0 of 15
 Rare
Gadsden County 14
0% 0 of 14
 Rare
Sarasota County 14
0% 0 of 14
 Rare
DeSoto County 12
0% 0 of 12
 Rare
Washington County 10
0% 0 of 10
 Rare

7 more Florida counties have 1 to 9 tested wells for nitrate, too few to rate.

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Where to get your well tested for nitrate in Florida

1

Free testing, with limits

Some Florida county health departments may test for certain chemicals for free, so call yours first. Check which tests it includes before you count on it for nitrate.

Florida's private well page
3

A mail-in kit

Fill the bottles at your kitchen tap and mail them back. We mark the kits that include nitrate.

Compare kits

Keep reading about wells in Florida

Questions people ask about nitrate in Florida

Is there nitrate in Florida well water?

Nitrate is widespread, over the limit in 15% or more of tested wells, in 2 of the 60 Florida counties with 10 or more tested wells. Across Florida, about 1 in 32 tested wells had nitrate over the EPA limit of 10 mg/L (111 of 3,501). Across all tested wells in the US it's about 1 in 12. That's less often than in the country as a whole. Counties still differ, so check yours below.

Where can I get my well tested for nitrate in Florida?

Some Florida county health departments may test for certain chemicals for free, so call yours first. If that doesn't cover you, use a lab certified by Florida for drinking water, or a mail-in kit that includes nitrate from a certified lab.

See Florida's list of certified labs, or compare mail-in kits.

Where these numbers come from

  • Lab tests: Water Quality Portal (USGS and EPA), well samples since 2000. A well counts as over if any of its tests was over the EPA limit of 10 mg/L. Wells tested for studies and monitoring, not a random sample of homes.
  • Likely overstated: our own check of who tested the wells, when and where. How we check.
  • State programs and links: Department of Health.