Well water in Monroe County, Florida

Name: Private well water quality in Monroe County, Florida
Creator: Well Water Nerd
License: Public domain (US federal government data)

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Testing recommended

tested well samples in Monroe County exceeded the EPA limit for nitrate (10 mg/L), based on public data from USGS Water Quality Portal.

640 test results across 9 contaminants from at least 92 wells, 1908 to 2021; nitrate has the most at 247. Data refreshed September 15, 2026.

Compiled by Nick at Well Water Nerd from public records. How these pages are built

An estimated 3,276 people in Monroe County get their drinking water from a private well, per USGS 2015 county water use. That is about 4% of residents.

Separately, the USGS national arsenic model estimates that <1% of the 3,276 people on private wells in Monroe County draw water above 10 ug/L, from geology and well depth rather than local tests.

What individual samples found

Each row summarizes every public sample for that contaminant inside Monroe County. Above limit means above the EPA maximum contaminant level; where EPA has no enforceable limit, the row shows a health guideline or nuisance level instead.

Contaminant	Above limit	Samples	Detected	Median	Highest	Limit
Nitrate 1908 to 1998	6%	247	75%	0.84	125	10 mg/L EPA limit
Lead 1986 to 2021	5%	40	85%	0	800	15 ug/L EPA limit
Arsenic 1986 to 2021	4%	27	81%	2	16	10 ug/L EPA limit
Fluoride 1908 to 2021	3%	40	100%	1.1	484	4 mg/L EPA limit
Copper 1988 to 2021	0%	11	91%	0.001	0.52	1.3 mg/L EPA limit
Chloride 1908 to 2021	no limit	165	100%	3,700	24,700	250 mg/L nuisance level
Iron 1908 to 2021	no limit	56	98%	145	65,000	300 ug/L nuisance level
Sodium 1939 to 2021	no limit	44	100%	5,200	12,500	20 mg/L health guideline
Manganese 1988 to 2021	no limit	10	100%	13.8	950	300 ug/L health guideline

Closer than the county

See the sampled wells near your address

The same records, drawn around one point: which wells within a few miles were sampled and what they found, how deep the wells next to you were drilled, and any leaking tank or cleanup site within a mile.

Check my address

What this means

The contaminants most often above their limit here are nitrate (6% of 247 samples), lead (5% of 40 samples), and arsenic (4% of 27 samples). A well next door can differ sharply from yours because bedrock fractures, well depth and plumbing all matter, so these rates describe the area, not your tap.

Chloride, Iron, and Manganese are widespread in local groundwater. They are mainly a staining and taste problem, but high manganese also carries a health advisory for infants.

What to test for in Monroe County

1
Nitrate
6% of 247 local samples were above the limit.
2
Lead
5% of 40 local samples were above the limit.
3
Arsenic
4% of 27 local samples were above the limit.
4
Fluoride
3% of 40 local samples were above the limit.
5
Coliform bacteria
Recommended for every private well, every year.
6
Chloride
Detected in 100% of local samples.
7
Manganese
Detected in 100% of local samples.
8
Volatile organic compounds (VOCs)
308 leaking underground storage tank sites on record locally.
9
Metals panel
1 hazardous waste site on record locally.

Test your Monroe County well for nitrate, lead and arsenic

Certified lab analysis of your own tap water, bottles and prepaid return shipping included. The Essential well panel covers arsenic, uranium, nitrate, lead, copper, manganese, iron, sodium and bacteria; radon and PFAS are add-ons.

Order the Tap Score well water test kit, from $209 Already tested? Upload the report

Just want bacteria checked first? Tap Score coliform and E. coli test, $99. Coliform and E. coli are the tests every well needs every year.

Want a quick look before paying for a lab? Home well water test strips on Amazon check hardness, iron, pH and nitrate in minutes. They are a screen, not a result: arsenic, bacteria, uranium and PFAS need a certified lab.

Affiliate links: the merchant pays us a commission and the price is the same for you. It does not change what the data above says. As an Amazon Associate we earn from qualifying purchases.

Where to get a well tested in Florida: certified labs, state programs and prices.

Already have results back? Get your lab report read against the Monroe County numbers, $29. Every line explained, ranked by what matters, with the fix for each.

Official help in Florida

Two places to start that are not selling anything: the state program that answers private well questions, and its list of labs certified to run drinking water tests. A certified lab is the difference between a result you can act on and a number.

Private Well Water Testing, Florida Department of Health
NELAP Certified Laboratory Search, Florida DEP

Contamination sources on record in Monroe County

FDEP records 308 leaking underground storage tank sites and 1 hazardous waste site in Monroe County, among 419 regulated sites in total. Groundwater does not follow property lines, so a well within a few hundred feet of one of these is worth testing for what that site could release.

308: leaking underground storage tank sitesGasoline and heating oil that leaked from tanks move through groundwater as benzene, MTBE and other volatile organic compounds.
1: hazardous waste siteSolvents, degreasers and metals from industrial sites can travel far in fractured bedrock.
110: other remediation projects

Treatment that fits the local profile

Nitrate

Point-of-use reverse osmosis; Anion exchange; Distillation

Lead

Point-of-use reverse osmosis; Certified lead-removal carbon filter; Neutralizing filter to raise pH and stop leaching

Arsenic

Point-of-use reverse osmosis; Adsorptive media (iron-based) whole-house; Anion exchange

Fluoride

Point-of-use reverse osmosis; Activated alumina; Distillation

Chloride

Point-of-use reverse osmosis; Distillation

Systems we would look at first

Some links below are affiliate links. If you buy through one, the merchant pays us a commission at no extra cost to you. It does not change which products we list or what the data says.

For nitrate

Under-sink reverse osmosis system

under-sink or countertop, about $300

Look for NSF/ANSI 58 certification listing the contaminant you need removed.

For nitrate

Aquasana SmartFlow reverse osmosis

under-sink or countertop, about $225

Certified to NSF/ANSI 58 and 53 to reduce arsenic (96%, pentavalent), fluoride (90%), lead (99%), nitrate, nitrite and PFOA/PFOS at the kitchen tap, with a remineralizer.

For lead

Aquasana Claryum 3-Stage under-sink filter

under-sink or countertop, about $175

Certified to NSF/ANSI 53 to reduce 99% of lead and 99.7% of PFOA and PFOS at the tap. Not a fix for arsenic, nitrate or bacteria.

For lead

Acid neutralizing filter

whole-house, at the point of entry, about $1,200

Raises pH so plumbing stops leaching lead and copper.

For arsenic

Whole-house arsenic and uranium filter

whole-house, at the point of entry, about $2,500

Adsorptive iron-based media; sized to your well yield.

For iron

Iron and manganese oxidizing filter

whole-house, at the point of entry, about $1,800

Air-injection or greensand media; fixes staining at the source.

Free, no obligation

Get on the list for a free in-home water test in Monroe County

No water treatment company serves Monroe County through Well Water Nerd yet. We are signing licensed companies on county by county: they test at your tap for free, walk you through the numbers, and quote treatment only if something needs fixing. Leave your details and you are first in line. Nothing is shared until a company joins for Monroe County, and you get an email naming it first.

Common questions

Is there arsenic in well water in Monroe County?

Arsenic was detected in 81% of 27 public well samples in Monroe County, and 4% were above the EPA limit of 10 ug/L. Arsenic has no taste or smell; a lab test is the only way to know your level.

How often should I test a private well in Monroe County?

Test for bacteria and nitrate every year. Test once for arsenic, uranium, radon, fluoride, manganese and PFAS, then again every three to five years or after any change in taste, color, or plumbing.

Counties near Monroe County

Closest first. Groundwater does not stop at a line on a map, so the next county over is a fair second opinion.

Want the numbers themselves? Download the Florida dataset as CSV, every county and town, with the sources named.

Sources

USGS Water Quality Portal: 640 samples in Monroe County. Data from the Water Quality Portal, a service of USGS, EPA and USDA; groundwater samples collected by USGS and cooperators. Retrieved September 3, 2026.
USGS national arsenic model (Ayotte 2017): estimated share of 3,276 people on private wells in Monroe County above 10 ug/L of arsenic, from geology, well depth and land use. County estimates of domestic well users with arsenic above 10 ug/L from the USGS national logistic regression model (Ayotte, Medalie and Qi, 2017), with private well population from the USGS 2015 county water-use compilation (Dieter and others, 2018). Retrieved September 15, 2026.
FDEP regulated sites: 419 regulated sites located in Monroe County. Petroleum contamination discharges and cleanup sites from the Florida Department of Environmental Protection. Retrieved September 17, 2026.

Non-detects count as samples and are treated as zero when computing medians. Exactly at the limit counts as not above it. A sample belongs to the town containing the well's reported coordinates.