Miami Dade County, Florida: drinking water report. Miami-Dade County draws its drinking water almost entirely from the Biscayne Aquifer, a shallow
Miami-Dade County draws its drinking water almost entirely from the Biscayne Aquifer, a shallow limestone aquifer that sits just below the surface across much of South Florida. The Miami-Dade Water and Sewer Department serves approximately 2.8 million residents, making it one of the largest water utilities in the southeastern United States. The Biscayne Aquifer is extraordinarily productive but also extraordinarily vulnerable – its porous limestone structure means surface contamination can reach drinking water wells within days, not years.
Saltwater intrusion is the defining water quality challenge in Miami-Dade. As sea levels rise and groundwater is pumped, saltwater from the Atlantic pushes further into the freshwater aquifer. The U.S. Geological Survey has documented the saltwater front advancing westward across the county, and several wellfields have already been relocated or abandoned due to rising chloride levels.
On PFAS, the EPA's UCMR5 data shows detections at sampling points across the county's system. Miami-Dade's proximity to Homestead Air Reserve Base and the former Opa-locka Airport adds military PFAS sources to the mix. Florida does not have state-specific PFAS standards, relying on federal EPA guidelines. According to a 2024 Florida Department of Environmental Protection survey, 23 public water systems in the county reported at least one PFAS compound above detection limits.
The Biscayne Aquifer's shallow depth means contamination events can affect water quality rapidly. We recommend checking your water regularly, not just once, since conditions can shift with seasonal pumping patterns and storm events.
For PFAS concerns, a reverse osmosis system is the most effective household solution. For saltwater intrusion-related taste and mineral issues, RO also helps. Our water filter guide covers which systems handle both scenarios. Pull your detailed report for multi-year trend data, and visit our Florida page for statewide patterns.
Drinking water is one exposure route. These federal datasets also cover Miami Dade County, FL.
The EPA places Miami Dade County, FL in Zone 2 - a moderate-risk category, with a predicted average indoor radon level between 2 and 4 pCi/L. Zone maps predict an area's radon potential from geology and existing indoor readings; they say nothing about a specific house. Testing is the only way to know your own level.
52% of homes in Miami Dade County, FL were built before 1980, and 8% before 1950. Residential lead paint was banned in 1978, so housing age is the strongest available proxy for lead-paint exposure. This describes the county's housing stock, not any one home.
Modelled annual fine-particle pollution (PM2.5) in Miami Dade County, FL averages 7.5 µg/m³, within the EPA's annual standard of 9 µg/m³. These are CDC modelled county estimates rather than readings from a specific monitor.
How radon zones work · Air quality by county · Lead exposure guide
Across 37 public water systems serving Miami-Dade County, FL with EPA lead testing on record, 4 (10.8%) reported a 90th-percentile lead result above the EPA's 15 ppb action level, and the median is 3.4 ppb. 7 water systems serving Miami-Dade County, FL carry a health-based EPA Safe Drinking Water Act violation.
| Most-cited violation type | Systems affected |
|---|---|
| Total Trihalomethanes (TTHM) | 3 |
| Lead and Copper Rule Revisions | 2 |
| Haloacetic Acids (HAA5) | 1 |
| Revised Total Coliform Rule | 1 |
| Ground Water Rule | 1 |
Source: EPA Lead and Copper Rule 90th-percentile tap sampling and EPA SDWIS Safe Drinking Water Act enforcement records, aggregated from the public water systems serving this county. Figures are counts of water systems, not a test of any individual home or tap.