Research · published 2026-07-07 · download the county-level CSV

1 in 14 Florida household water wells sits within a quarter mile of a documented fuel leak

Florida does not require anyone to test a private well after it is drilled — sampled once at construction, then never again unless the owner pays for it. The state also carries one of the country’s largest backlogs of underground fuel-tank leaks it has documented but not finished cleaning up. We mapped where those two facts meet.

Comparing 498,747 Florida household water wells (FL WMD/county) against the U.S. EPA’s UST Finder database of underground-storage-tank releases — documented leaks of gasoline, diesel, and heating oil at 34,691 Florida sites:

• 34,609 household water wells (6.9%) lie within 1,320 ft (a quarter mile) of at least one documented petroleum release.
• 11,368 (2.3%) lie within a quarter mile of a release the state still lists as open — reported but not yet cleaned up (EPA snapshot, 2026-06-12).

None of these households is required to test their water. Public water systems near the same leaks are monitored on a federal schedule; private wells fall entirely outside that law.

EPA’s own UST Finder analysis estimated 58,651 Florida private domestic wells within 1,500 ft of an active leaking-tank site — the highest count of any state. EPA’s FY2025 performance report puts Florida’s cleanup backlog at 7,856 open releases, the largest in the nation.

Counties with the most household wells near an open leak

Download the full county table (CSV)

What this does and does not say

• Proximity is not contamination. Distance from a documented release is a screening signal, not evidence any specific well is affected. Whether a plume reaches a well depends on hydrogeology, depth, direction, and remediation history. Testing is the only way to know — which is the point: no one is required to.
• What we counted. Florida-recorded household water wells, excluding wells flagged abandoned and all monitoring, irrigation, and public-supply wells. This is the best public proxy for homes on well water, though some records are older wells since replaced or disconnected.
• Coverage. Our Florida well data aggregates four public sources covering 37 of 67 counties (the South Florida, Southwest Florida and St. Johns water management districts plus Lee and Miami-Dade counties). The figures above count domestic wells only within that coverage — not the whole state.
• “Open” status lags. The EPA release snapshot dates to 2026-06-12; states close releases every year, so the current open count is somewhat lower. The “any documented release” figure — cumulative history — is not affected.

Methodology

• Wells: 498,747 Florida household water wells with coordinates from FL WMD/county (refreshed weekly; see our general methodology).
• Releases: 34,691 Florida release sites with coordinates from EPA UST Finder (10,203 listed open in the snapshot).
• Join: great-circle (haversine) distance, well-to-release, threshold 1,320 ft. Each well is counted once no matter how many releases are nearby.
• Why a quarter mile: peer-reviewed work behind UST Finder used 1,500 ft as the outer bound of observed petroleum plume lengths (Weaver et al. 2017); we use a tighter 1,320 ft, so our threshold is the more conservative of the two.
• Checks: results were spot-verified at the address level (flagged wells and their nearest release share streets and ZIP codes) and screened for coordinate artifacts (no bulk co-located records).

Sources

• Florida well records: FL WMD/county
• EPA UST Finder (release locations and status)
• EPA, Semiannual Report of UST Performance Measures, FY2025 (state cleanup backlogs)
• Weaver, Murray & Kremer (2017), Science of the Total Environment 609:1589–1599 (plume-length basis for the distance threshold)
• Murray, Hall, Weaver & Kremer (2021), JAWRA 57(5):828–843 (EPA’s domestic-well proximity estimates)
• ASTSWMO/EPA UST Finder briefing (state-by-state wells-near-releases counts)