Losing water sends many owners straight to panic and a repair call, but the first job is simple: separate evaporation from a real leak. The bucket test settles that in a day and saves you chasing a problem that was only the weather.
What you are seeing
The water level drops faster than usual, you are topping up often, or the level keeps falling even when the pool is not in use. The equipment pad or the ground around the pool may be damp.
Possible causes
- Normal evaporation Most pools lose a quarter inch to half an inch a day to evaporation, more in hot, dry, or windy weather. This is not a leak.
- Splash-out and backwash Heavy swimming, an overflowing skimmer, or frequent backwashing removes water that looks like a leak but is not.
- A plumbing or fitting leak A leak on the pressure side often shows as wet ground near the return lines or the pad, and can worsen when the pump runs.
- A shell, liner, or fitting leak A tear in a vinyl liner, a crack in the shell, or a bad seal at a light, skimmer, or return can let water out steadily.
How to check
- Run the bucket test: fill a bucket, mark the water line inside and the pool line outside, float it on a step, and compare the drop after 24 hours.
- If both drop the same, it is evaporation. If the pool drops more than the bucket, you likely have a leak.
- Note whether the level stabilizes at a fitting, a light, or the skimmer mouth, which points to the leak's height.
- Compare loss with the pump on versus off to separate pressure-side from suction-side leaks.
How to fix it
- Rule out evaporation first Run the bucket test before assuming a leak. A cover dramatically cuts evaporation and confirms the cause.
- Find the leak's height Let the pool drop on its own. Where it stops often reveals the leaking fitting or tear, since water only escapes above that point.
- Test the equipment pad Watch the pad and return lines with the pump running. Wet spots that appear under pressure point to a plumbing leak.
- Seal or repair the source Reseal a leaking light or return fitting, patch a liner tear, or call a leak-detection service for buried plumbing leaks.
How to prevent it
- Use a cover to cut evaporation and keep the real picture clear.
- Keep the water at the middle of the skimmer so the pump never draws air.
- Inspect fittings, the liner, and seals each season before loss becomes severe.