Most Central Florida pools lose about a quarter inch of water a day to evaporation, close to 2 inches a week. If your pool drops much faster than that, or keeps dropping when the weather is mild, a 3-day bucket test will tell you whether you have a leak.
How Much Water Does a Pool Lose to Evaporation?
The common rule of thumb is about 1/4 inch a day. Florida’s own numbers line up: a U.S. Geological Survey study of Lake Okeechobee measured about 72 inches of evaporation a year, roughly 0.2 inch a day on average, with the biggest days in summer and on dry, windy days after winter cold fronts.
At 1/4 inch a day, here is what that means in gallons:
| Pool surface | Per day | Per week | Per month |
|---|---|---|---|
| 12 x 24 ft (288 sq ft) | about 45 gal | about 315 gal | about 1,350 gal |
| 15 x 30 ft (450 sq ft) | about 70 gal | about 490 gal | about 2,100 gal |
| 20 x 40 ft (800 sq ft) | about 125 gal | about 875 gal | about 3,750 gal |
The math: 1 inch of water over 1 square foot is about 0.62 gallons.
What Makes a Pool Evaporate Faster?
- A heated pool in cool weather. Warm water under cold, dry air evaporates fast, which is why a heated pool can drop noticeably in winter.
- Wind and cold fronts. Dry air moving across the surface pulls water off quickly.
- Water features. Spillover spas, waterfalls, bubblers and vanishing edges throw water into the air and add surface area.
- Sun and no screen. Direct sun and open air speed things up; a screen enclosure slows the wind.
What helps: run water features only when you are using the pool, lower the heater setting when no one is swimming, and consider a cover for a heated pool.
Leak or Evaporation? Do the Bucket Test
- Turn off the autofill and do not add water or backwash during the test.
- Fill a bucket with pool water and set it on a pool step so the bucket’s water level matches the pool’s.
- Mark the water level inside the bucket and on the pool tile.
- Wait 2 to 3 days with the pump running on its normal schedule.
- Compare. If the pool and the bucket dropped the same amount, it is evaporation. If the pool dropped more, you likely have a leak.
- Repeat with the pump off. If the pool loses more with the pump running, the leak is probably in the plumbing.
Signs It Is a Leak
- The pool drops well over 1/4 inch a day for days in a row, in normal weather.
- The water stops dropping at the same spot every time, often at a skimmer, a light or a fitting.
- Soggy ground, standing water or settling near the pool or equipment pad.
- Cracks in the tile line or shell, or air bubbles in the pump basket.
- You are topping off more often and the water bill is creeping up.
Let Us Find It
Southern Pool Care handles leak detection and the repair, from plumbing and fittings to equipment. See our pool repair service, browse the pool care FAQ, or read more in our pool maintenance tips.
Losing more than a quarter inch a day?
Southern Pool Care finds and fixes pool leaks and runs weekly service across Sanford, Lake Mary, Heathrow, Longwood, Winter Springs, Oviedo, Winter Park and Maitland, from the team that builds Central Florida luxury pools.