Draining a Pool in Florida: Groundwater, Valves and Rules

A pool shell is built to hold water in, and an empty one sits in the ground with nothing pressing down on it. Where groundwater is close to the surface, it can push up on the empty shell. That is why Florida’s building code requires a pressure relief device in pools where a water table is expected, and why draining a pool in Lee County is a job for a licensed contractor.

Why an empty pool can float

A valve maker describes the hydrostatic relief valve as a part that “helps prevent swimming pool damage due to hydrostatic pressure beneath the pool shell when the pool is drained.” Lee County soils can hold water close to the surface: the USDA’s description of the Matlacha soil series, whose type location is in Lee County, gives a “depth to seasonally high water table” of 18 to 42 inches. That is a soil series, not a measurement under any particular pool, but it shows why the code asks the question.

The hydrostatic relief valve

The Florida Building Code, Residential (8th edition, 2023), section R4501.21.4, says: “In areas of anticipated water table an approved hydrostatic relief device shall be installed.” Plastic liner pools, “where there is no structural bottom to the pool”, are the exception. Before a pool is drained, the contractor should know where the valve is and whether it works. As of October 2026 the 8th edition (2023) is the code in force; the Florida Building Commission’s October 2026 workplan lists the 9th edition’s effective date as 12/31/2026.

When to drain

No source names a best month. The rain is what to plan around: at Fort Myers’ Page Field, 38.47 of the year’s 57.41 inches of rain fall from June to September (NOAA normals, 1991-2020).

Where the water can go

The Florida Department of Environmental Protection says dechlorinated pool discharges “are authorized in Florida in accordance with 62-624.200(2)(q), F.A.C.; provided that they do not cause a violation of water quality standards.” Its guidance: let the water stand “for at least 48 hours after the last addition of chlorine or until the free chlorine residual is < 0.01 mg/L”, direct the discharge “over a vegetated surface so that some level of filtration can occur”, and remember that “direct discharges to surface waters are not allowed.” No Cape Coral, Fort Myers or Lee County rule on draining pools was found; ask your city or the county before you drain.

Who drains a pool for repair

Florida law includes “the substantial or complete draining of a swimming pool … for the purpose of repair or renovation” in the scope of a swimming pool/spa servicing contractor (s. 489.105(3)(l), Florida Statutes). Look the contractor up at myfloridalicense.com first. If the pool is being drained to be resurfaced, pool resurfacing covers the rest of the job, and pool startup after plaster covers the refill.