Every pool loses water to evaporation. In Brentwood's hot, dry, often windy summer afternoons, it can lose a surprising amount. The question is whether what you're seeing is more than evaporation. The bucket test answers that with nothing more than a bucket and a marker.
How much evaporation is normal?
A commonly cited average is about a quarter inch a day, but it varies a lot with heat, wind, humidity, and whether the pool is heated or has water features running. On hot, windy days, more is normal. That's why a single number isn't a reliable test, and why the bucket test compares the pool against a bucket sitting in the same conditions.
How to do the bucket test
- Bring the pool to its normal level and turn off the auto-fill.
- Fill a 5-gallon bucket with pool water to about an inch from the top.
- Set the bucket on the pool step, weighted with a brick or rock so it doesn't float or tip.
- Mark the water level inside the bucket, and the pool's water level on the outside of the bucket.
- Run the pool normally for 24 hours. Skip it if rain is forecast.
- Compare. If the pool dropped more than the water inside the bucket, the difference is a leak.
Run it twice
Do one 24-hour test with the pump on its normal schedule and one with the pump off. If the pool loses more with the pump running, the leak is likely on the pressure side (return lines or equipment). If it's the same either way, it may be in the shell, a fitting, or a suction line.
Other clues
- The level stops at a certain height, like the bottom of the skimmer opening or the pool light. The leak is probably at that spot.
- Wet or soft ground between the pool and the equipment pad, or around the pad.
- Air bubbles in the returns or a pump that loses prime, which can mean a suction-side leak.
- New cracks in the deck, coping, or plaster, or tiles coming loose.
- A higher water bill than the same months last year.
If it's a leak
Keep the pool topped up so the pump doesn't run dry, write down how much it's losing per day, and get it located. Professional detection uses dye, pressure testing, and listening equipment to find the leak before anything is cut open. See pool leak detection for how that works and what it usually costs.
Frequently asked questions
Why is my pool losing 1 inch of water a day?
A steady inch a day is more than evaporation usually accounts for. Run the bucket test to confirm; if the pool drops more than the bucket, it's leaking.
How long should a bucket test run?
At least 24 hours, without rain and with the auto-fill turned off. Running it once with the pump on and once with it off gives more information.
Can a pool leak on its own stop?
Sometimes the level stops dropping once it falls below the leak, like a skimmer crack. The leak is still there, and it will keep leaking whenever the pool is filled back up.
Cost ranges and legal notes on this page are general information, not a quote or legal advice. Prices vary by job; get a written quote for your pool.