Troubleshooting guide
Pool losing water: leak or evaporation?
Pools lose water to evaporation and splashing every day. Before you hunt for a leak, find out if you actually have one.
Do the bucket test
Hayward's guide describes it simply: fill a bucket with pool water and set it on the top step so it's partly submerged and stays at the pool's temperature. Mark the water level inside the bucket and on the pool wall. Wait, then measure. If the pool dropped more than the bucket, you have a leak.
Turn off any auto-fill and don't swim or backwash during the test. Running it once with the pump on and once with it off can hint at which side of the plumbing is leaking.
Where leaks usually hide
- Skimmers and suction outlets: Hayward calls these frequent culprits.
- The equipment pad: look for drips at the pump, filter, heater and valves. A leak from under the pump motor is usually the shaft seal (Pentair).
- Underground pipes: look for a sunken or unusually green patch of ground.
- Liner tears, light niches and fittings in the pool itself.
Keep the water level up while you look: if it drops below the skimmer, the pump draws air and can lose prime.
When to call in a pro
Underground and structural leaks need a leak detection company with pressure-testing gear. A tech on video can help you rule out the equipment pad first, identify the part if it's a pump seal or union, and tell you when it's time for leak detection.
Common questions
How much water loss is normal for a pool?
It varies with heat, wind and use. Hayward notes evaporation alone can drop the level by up to about 2 cm (under an inch) a day in hot, windy weather. The bucket test tells you whether your loss is more than evaporation.
How do I do a pool bucket test?
Fill a bucket with pool water, set it on the top step so it's partly submerged, and mark the water level inside the bucket and on the pool. After a day, if the pool dropped more than the bucket, you likely have a leak.
Why is water leaking under my pool pump?
Water from under the motor usually means a worn shaft seal. Other common spots are the strainer lid O-ring and the unions. Turn the pump and breaker off before you look closely.
Related guides
Pump not priming
Pump runs but the basket won't fill. Almost always air or water level.
Read the guideFilter pressure high or low
The gauge tells you when to clean the filter, and when something upstream is wrong.
Read the guideElectrical safety & pool lights
Tingling, flickering lights or a GFCI that won't reset. Treat it as an emergency.
Read the guideVariable-speed pump codes
Priming, overheat, overcurrent and voltage alarms across the big three brands.
Read the guideSources
- Hayward: Help! I think my pool is leaking! (evaporation, the bucket test, where leaks hide)
- Pentair, IntelliFlo3 VSF / IntelliPro3 VSF installation and maintenance guide: priming, drive LEDs, troubleshooting chart, alarms and warnings
Brand names belong to their owners. Pool Helpline isn't affiliated with or endorsed by any manufacturer. Steps and codes vary by model and year, so always check your own owner's manual.
