Pool Losing Water in South Florida? Leak vs. Evaporation — The 24-Hour Bucket Test, Real 2026 Repair Costs & When to Call a Pro

Normal South Florida summer evaporation runs 1/4–1/2 inch per day, more with wind or screen-off pools. The 24-hour bucket test separates them definitively: tape a bucket of pool water to the steps, mark both levels, wait 24 hours with the pump running, compare. If the pool drops the same as the bucket, it's evaporation; if the pool drops more, you have a leak. Typical 2026 South Florida leak detection runs $300–$600 (dye + pressure test). Repairs run from $150 (skimmer throat reseal) to $2,800+ (mainline plumbing under deck). 90% of homeowner "leak" calls are evaporation in disguise during May–October.

In South Florida, a typical uncovered residential pool evaporates 1/8"–1/4" per day in winter and 3/8"–1/2" per day during May–June (hottest, driest stretch before rainy season). July–September evaporation is similar by daytime rate but partially offset by afternoon storms refilling the pool. Screen-off pools lose 30–50% more due to wind exposure. Heated spas attached to a pool add another 1/8"–1/4" per day. So a normal weekly drop of 1.5–3.5 inches during summer is not a leak — it's exactly what an exposed Florida pool does.

Fill a 5-gallon bucket with pool water to about 4 inches from the top and place it on the second step inside the pool so the bucket water and pool water are at similar temperature. Mark both water levels with tape — the level inside the bucket and the level outside (on the pool tile). Run your pump on its normal schedule. Do not add water, do not run the autofill, and do not swim during the test. Return in 24 hours and measure the drop on each. If the bucket drop equals the pool drop, you have evaporation, not a leak. If the pool drops more than the bucket, you have a leak — the difference (in inches) tells you how big. Run it twice if conditions were windy or your pool is screen-off, since single-test results can swing.

Across our service corridor, four locations account for about 95% of confirmed leaks: (1) skimmer throat or face cracks — about 35% of leaks, where Florida heat-cycle expansion plus occasional freezes break the bond between throat plastic and pool shell at 8–15 years of age; (2) equipment pad fittings — about 25%, including pump seals, union o-rings, valve diverters, and filter band clamps, all visible on a walk-around; (3) underground plumbing under deck or yard — about 20%, where PVC cracks from settlement, root pressure, or aged schedule-40 in salt corridors; (4) light niche or main drain — about 15%. Visible plaster or shell cracks are rare (about 5%).

It depends on the type. Equipment-pad leaks (pump seals, unions, valves, filter o-rings) and skimmer throat leaks are usually found and fixed by a competent weekly service tech during a normal route visit — those are visual and tactile. Underground plumbing leaks, light niche leaks, main drain leaks, and any leak where the bucket test shows a significant gap with no visible source require a leak-detection specialist with ultrasonic and pressure-test equipment. A reasonable rule: if the bucket test shows under 1/2" daily gap and you can see a damp equipment pad, your weekly tech handles it. Anything more than that or with no visible source, call a leak-detection specialist for a $300–$600 diagnostic.

A one-time leak detection call from a specialist runs $300–$600 in our service corridor — that includes dye testing at all visible suction and return points, pressure testing the plumbing lines, equipment-pad isolation with valves, and a written report identifying the leak location and estimated repair cost. If the leak is at the light niche or main drain and requires a diver, expect $400–$700. Skimmer-throat dye tests by a weekly service tech are typically free as part of the route visit. Repairs are separate — see the cost table for ranges from $150 (skimmer throat reseal) up to $2,800 (underground plumbing under deck).

Yes — and it's one of the easiest 'leaks' to miss because the pool looks fine. Most South Florida pools have an autofill valve plumbed to city water. If your pool is leaking but the autofill is replacing the loss in real time, the pool level never visibly drops — instead, your water bill climbs $30–$200/month. To check: shut off every water-using appliance in the house, then look at the water meter dial. If the dial is still spinning, water is being consumed somewhere — either the autofill float is stuck open and masking a real pool leak, or there's a service-line leak between the meter and the pool. Both are real problems worth diagnosing.

That's the classic signature of a pressure-side leak — the return plumbing carrying water from the filter back to the pool is under pump pressure, and any crack in it gets actively pushed open while the pump runs. Common sources: cracked return line under the deck, a leaking jet fitting, or a failure at the heater or filter outlet. Conversely, if your pool only loses water with the pump off, look at the suction side or the shell — suction lines sit under vacuum while the pump runs (they pull air in rather than push water out) and only drain by gravity once it stops. Knowing which side it is narrows the repair scope significantly.

In our service corridor, yes — about 35% of confirmed leaks at pools 8–15 years old originate at the skimmer throat (the white plastic neck behind the basket). The bond between the throat and the pool shell fatigues from constant heat-cycle expansion (95°F summer days, 65°F summer nights) plus occasional freeze cycles in winter. The signature: water drops to mid-skimmer height and then stops. Confirmed easily with a few drops of pH dye reagent at the throat — if dye is drawn into a crack with the pump running, you've found it. Repair is hydraulic cement or a foam-injection kit, $150–$450, often same-visit during a service call.

An autofill is a small valve plumbed from city water into a niche on the pool — usually in the skimmer or a dedicated autofill box on the deck. It has a float (similar to a toilet tank float) that opens the city-water valve when the pool water drops below a set level, refilling automatically. They fail two ways: stuck open (water runs constantly even at full pool level, water bill triples) or stuck closed (pool drops with no autofill response). To check stuck-open: shut off the autofill isolation valve (usually on the equipment pad or in the autofill box). If your water-meter dial stops moving, the autofill was running. Replace the float assembly ($25–$60 part, 15-minute service).

Call us if any of these apply: (1) the bucket test shows a clear gap of 1/2" or more per day; (2) the water level has dropped past the skimmer mouth (the pump may be running dry, a separate $1,400–$2,400 problem); (3) you see a soggy spot in the yard near the pool or a damp area on the deck that doesn't dry out; (4) the equipment pad shows white efflorescence (powdery deposit) or a constant wet patch; (5) your water bill has jumped significantly with no other plumbing changes; (6) the pool only loses water with the pump running, or only with the pump off (suction-side or pressure-side diagnostic narrows the problem). Free on-site evaluation included for weekly-route clients.