Private wells
Florida well water: who's on a well and what to test for
People on private wells
2,017,100
Homes on wells
9.0%
Est. above arsenic limit
50,900
Every Florida county
Sorted by people on private wells. Arsenic and nitrate are modeled for typical wells in the county, not measured at yours; depth is the median of domestic well records.
| Duval County | 177,700 | 17% | 1.8% | 0.0 | n/a |
| Marion County | 137,500 | 36% | 1.0% | 1.3 | 90 ft |
| Brevard County | 102,100 | 16% | 1.7% | 0.0 | n/a |
| Volusia County | 88,400 | 15% | 1.4% | 0.0 | n/a |
| Hillsborough County | 81,900 | 5% | 1.5% | 0.0 | 100 ft |
| Monroe County | 69,100 | 86% | 4.4% | 0.0 | n/a |
| Lake County | 68,900 | 17% | 1.3% | 0.1 | n/a |
| Clay County | 67,200 | 33% | 1.8% | 0.0 | n/a |
| Pasco County | 61,600 | 10% | 2.4% | 0.1 | n/a |
| Orange County | 56,800 | 4% | 1.3% | 0.0 | n/a |
| Citrus County | 56,300 | 35% | 2.5% | 0.1 | n/a |
| Seminole County | 50,400 | 10% | 1.2% | 0.1 | n/a |
| Polk County | 50,200 | 6% | 1.2% | 0.1 | n/a |
| Putnam County | 49,000 | 68% | 1.6% | 0.0 | n/a |
| Miami-Dade County | 46,000 | 2% | 2.8% | 0.8 | n/a |
| Alachua County | 43,900 | 16% | 1.1% | 0.5 | 112 ft |
| St. Johns County | 41,200 | 16% | 1.5% | 0.0 | n/a |
| Nassau County | 37,700 | 38% | 1.8% | 0.0 | n/a |
| Indian River County | 34,200 | 20% | 1.8% | 0.0 | n/a |
| Leon County | 33,900 | 11% | 2.2% | 0.3 | 170 ft |
| Jackson County | 29,800 | 68% | 0.8% | 1.7 | 140 ft |
| Columbia County | 29,700 | 43% | 1.2% | 0.3 | 120 ft |
| Bay County | 29,400 | 12% | 4.0% | 0.0 | 200 ft |
| Collier County | 27,400 | 5% | 2.2% | 0.0 | n/a |
| Lee County | 26,300 | 3% | 1.5% | 0.0 | n/a |
| Walton County | 25,600 | 21% | 2.6% | 0.1 | 260 ft |
| Suwannee County | 25,100 | 57% | 1.6% | 1.0 | 120 ft |
| Sumter County | 24,700 | 11% | 2.1% | 0.2 | n/a |
| Palm Beach County | 23,500 | 1% | 1.4% | 0.0 | n/a |
| Levy County | 22,300 | 51% | 1.2% | 0.4 | 69 ft |
| Hernando County | 21,300 | 11% | 3.3% | 0.0 | 125 ft |
| Santa Rosa County | 19,800 | 10% | 1.7% | 0.8 | 125 ft |
| Gadsden County | 18,300 | 43% | 1.6% | 0.0 | 340 ft |
| Sarasota County | 18,200 | 3% | 1.8% | 0.0 | n/a |
| Highlands County | 17,400 | 16% | 1.4% | 0.1 | n/a |
| Washington County | 16,100 | 70% | 1.9% | 0.2 | 200 ft |
| Bradford County | 15,400 | 58% | 1.3% | 0.0 | 120 ft |
| DeSoto County | 15,300 | 40% | 2.3% | 0.0 | n/a |
| Wakulla County | 15,000 | 48% | 2.2% | 0.1 | 97 ft |
| Baker County | 14,800 | 58% | 1.4% | 0.0 | 180 ft |
| Holmes County | 13,500 | 76% | 1.4% | 0.1 | 240 ft |
| Okaloosa County | 13,500 | 6% | 2.1% | 0.2 | 280 ft |
| Okeechobee County | 13,100 | 30% | 1.1% | 0.0 | n/a |
| Osceola County | 12,900 | 3% | 1.3% | 0.0 | n/a |
| Martin County | 12,900 | 6% | 2.1% | 0.0 | n/a |
| Broward County | 12,100 | 1% | 1.9% | 0.0 | n/a |
| Hendry County | 12,000 | 32% | 3.2% | 0.0 | n/a |
| Jefferson County | 10,800 | 72% | 1.4% | 0.2 | 200 ft |
| St. Lucie County | 10,100 | 3% | 1.3% | 0.0 | n/a |
| Gilchrist County | 10,000 | 60% | 1.2% | 1.0 | 85 ft |
| Hardee County | 9,900 | 41% | 1.3% | 0.0 | n/a |
| Calhoun County | 9,700 | 72% | 2.3% | 0.1 | 160 ft |
| Madison County | 9,300 | 56% | 1.5% | 0.3 | 120 ft |
| Taylor County | 9,300 | 45% | 1.6% | 0.0 | 44 ft |
| Escambia County | 8,900 | 3% | 2.6% | 0.8 | 120 ft |
| Flagler County | 8,400 | 8% | 1.4% | 0.0 | n/a |
| Dixie County | 8,400 | 54% | 1.3% | 0.1 | 57 ft |
| Manatee County | 6,900 | 1% | 1.8% | 0.0 | n/a |
| Union County | 6,800 | 55% | 1.3% | 0.0 | 140 ft |
| Hamilton County | 5,500 | 47% | 1.6% | 0.2 | 150 ft |
| Gulf County | 5,200 | 35% | 1.6% | 0.0 | 180 ft |
| Lafayette County | 4,500 | 68% | 1.7% | 0.3 | 77 ft |
| Liberty County | 4,200 | 69% | 2.5% | 0.0 | 200 ft |
| Glades County | 4,100 | 28% | 2.5% | 0.0 | n/a |
| Charlotte County | 3,200 | 1% | 3.1% | 0.0 | n/a |
| Franklin County | 2,400 | 17% | 2.3% | 0.0 | 100 ft |
| Pinellas County | 280 | 0% | 2.8% | 0.0 | 100 ft |
Shading: red is among the highest counties nationally, amber the middle, green the lower range. Click a column to sort.
Most well users above the arsenic limit
- Palm Beach County: about 3,500 people
- Osceola County: about 3,300 people
- Lee County: about 2,700 people
- St. Lucie County: about 2,400 people
- Clay County: about 2,100 people
Test first, then treat what the test finds
We may earn a commission from links below, at no cost to you. Picks follow the testing order, not who pays. How we make money.
1. Certified lab well test
Start here, every year
A mail-in kit analyzed by a certified lab measures bacteria, nitrate, arsenic, metals and more. Test strips cannot measure arsenic or uranium reliably.
2. Sediment pre-filter
Sand, silt or cloudy water
A 5-micron cartridge after the pressure tank catches sand, silt and rust before they reach fixtures or other filters. Cartridges are cheap and swap every few months.
3. Iron and sulfur filter
Orange stains or rotten-egg smell
Air-injection or oxidizing-media filters remove orange staining and rotten-egg smell. Size one from a lab result for iron, manganese and hydrogen sulfide.
4. UV disinfection system
Coliform bacteria in a test
Inactivates bacteria and viruses; usually for private wells or after boil notices.
5. Under-sink reverse osmosis
Arsenic, nitrate or uranium in a test
The most thorough option for drinking water: PFAS, lead, nitrate, arsenic and more. Look for NSF/ANSI 58.
6. Whole-house well filter
Several problems at once
Multi-stage sediment and carbon for every tap. Add UV if bacteria shows up, and choose stages from your lab results, not a guess.
Questions
Which Florida counties rely most on wells?+
By share of homes: Monroe County (86%), Holmes County (76%), Calhoun County (72%), Jefferson County (72%), Washington County (70%). By number of people: Duval County (177,700), Marion County (137,500), Brevard County (102,100).
Is arsenic a problem in Florida wells?+
USGS estimates about 50,900 Florida well users have water above the 10 microgram per liter arsenic limit that applies to public systems, the largest numbers in Palm Beach County, Osceola County, Lee County. Arsenic has no taste or smell, so only a lab test finds it.
Do I have to test my well when I sell a house in Florida?+
We could not confirm a statewide rule for Florida. Check with your county health department. Buyers can still make a lab test a condition of the offer.
How often should I test my well?+
No federal law covers private wells. EPA's drinking water limits apply to public water systems, so testing and treating a private well is up to the owner. EPA and CDC recommend testing at least once a year for coliform bacteria, nitrate, pH and total dissolved solids, and testing for arsenic, uranium, radon and other local concerns based on where you live.
Well-user counts, arsenic and nitrate figures are each a modeled estimate built from national datasets, not a count of tested wells, and well depths summarize drilling records rather than every well. Your own well can be very different from the county average, which is why the only answer for your home is a lab test. Sources: EPA Office of Research and Development, Water Source 2020 (private well estimates by census block); CDC Environmental Public Health Tracking, Well Water Index (from USGS nitrate and arsenic models); USGS, county-level domestic well population with arsenic above 10 micrograms per liter (Ayotte and others, 2017); USGS Synthesized Domestic Well Database for the Conterminous United States (SynDWell-US), McCarthy and others, 2025 (depth, where a county has 30+ usable records).