Last reviewed and updated: 2026-09-24
A pool in the Marietta climate losing roughly a quarter to half an inch a day in summer is almost certainly evaporating normally. Consistently more than that indicates a leak. The bucket test settles it by exposing a bucket of water to the same conditions as the pool, so both lose water to evaporation at the same rate: if the pool drops faster than the bucket, the difference is the leak.
The bucket test separates evaporation from a real leak; after that it is pool leak detection work. A pool with an auto-fill hides itself and shows up only as a higher water bill.
What is normal loss
| Condition | Typical daily loss |
|---|---|
| Hot, dry, windy summer day | Up to roughly half an inch or slightly more |
| Typical Georgia summer day | Roughly a quarter to half an inch |
| Mild spring or autumn day | Well under a quarter of an inch |
| Cool, humid or overcast | Minimal |
| Heated pool in cool weather | Higher than expected: heat drives evaporation |
| Heavy swimmer use | Add splash-out, which is real loss but not a leak |
Wind and heating both increase evaporation. An exposed pool on a windy ridge loses more than a sheltered one, and a heated pool in cool weather can lose a surprising amount. Both are normal, and both get mistaken for leaks.
The bucket test
- Fill a bucket with pool water and stand it on a step so the water inside sits at roughly the same level as the pool water outside it.
- Mark both levels. The water level inside the bucket, and the pool level on the outside of the bucket.
- Leave it 24 hours with the pump on its normal schedule. Do not add water and do not swim.
- Compare. Equal loss means evaporation. The pool dropping further than the bucket means the difference is a leak.
- Repeat with the pump off for another 24 hours. A different loss rate between the two runs tells you which side of the system is at fault.
What the pump tells you
| Loss pattern | Likely location |
|---|---|
| Worse with the pump running | Pressure-side return plumbing |
| Worse with the pump off | Suction-side plumbing, or the shell |
| Same either way | The shell, or a fitting at or below the water line |
| Stops at a particular level | The leak is at that level: skimmer throat, light niche or tile line |
| Air bubbles from the return jets | Suction-side leak drawing air into the system |
| Level never drops but the bill is high | An automatic fill valve masking the leak |
Turn the auto-fill off before testing. An automatic fill keeps the level looking perfect while the water passes through your meter continuously. It is the single most common reason a pool leak goes unnoticed for months.
Frequently asked questions
How much pool water loss is normal?
Roughly a quarter to half an inch a day in a Georgia summer is normal evaporation, less in mild or humid weather. Consistently more than that suggests a leak. Wind, heating and swimmer splash-out all increase normal loss.
How do I do the bucket test?
Fill a bucket with pool water and stand it on a step so the inside water level matches the pool. Mark both levels, leave it 24 hours with the pump on its normal schedule without adding water or swimming, then compare. If the pool dropped more than the bucket, that difference is a leak.
Does it matter whether the pump is on or off?
It matters a great deal. Loss that is worse with the pump running points to pressure-side return plumbing; worse with the pump off points to suction-side plumbing or the shell; the same either way points to the shell or a fitting. Running the bucket test both ways is the most useful diagnostic you can do yourself.
My pool level never drops but my water bill is high. Why?
An automatic fill valve is almost certainly masking a leak: it keeps topping the pool up so the level looks perfect while water passes through your meter continuously. Turn the auto-fill off and run the bucket test.
Where do pool leaks usually happen?
The skimmer throat, the light niche, the main drain, return fittings, the steps, and the plumbing runs under the deck. If the level stops dropping at a particular height, the leak is at that height, which narrows it considerably.
Do I have to drain the pool to find a leak?
Almost never, and it is best avoided, draining a pool can cause structural damage. Plumbing runs are pressure-tested individually, dye testing identifies shell and fitting leaks with the water still, and listening equipment locates pressurized leaks under the deck.