01
The purpose
What does this calculator estimate?
The standard DIY leak test: compare your pool's drop to a bucket's to separate a leak from evaporation.
Water Loss & Leaks · E2
Pool Bucket Test Leak Calculator
The standard DIY leak test: compare your pool's drop to a bucket's to separate a leak from evaporation.
Measure the inputsRun the test with the pump off and the pool full, in calm weather, for 24 hours.
Read the full resultPlace the bucket on a pool step, weighted, with its water level matched to the pool.
Check the boundaryIf pool and bucket drop equally, your loss is evaporation, not a leak.
Useful forWater Loss & LeaksPlanningComparisonVerification
Live calculation
Bucket test inputs
✓ Checked May 2026
Enter the pool drop and the bucket drop over the test.
Estimated rate
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Enter the required values to calculate.
Enter the known values. Let the engine handle the calculation.
✓ Formula checked↻ Live result○ No account needed
Planning estimate only. Confirm product labels, equipment specifications, qualified-professional advice and local requirements before acting.
The result, explained
Use the Pool Bucket Test Leak Calculator result with context.
The standard DIY leak test: compare your pool's drop to a bucket's to separate a leak from evaporation.
02
The tool
What information does it use?
- Pool surface area: To convert inches to gallons.
- Pool water drop: Inches the pool fell over the test period.
- Bucket water drop: Inches the bucket fell — this is pure evaporation.
- Test duration: Hours the test ran (24 is standard).
03
The method
How to use this calculator
- Pool surface areaTo convert inches to gallons.
- Pool water dropInches the pool fell over the test period.
- Bucket water dropInches the bucket fell — this is pure evaporation.
- Test durationHours the test ran (24 is standard).
04
The relationship
The formula in plain English
Net leak = Pool drop − Bucket drop (the bucket isolates evaporation)
Leak gallons/day = (net inches ÷ 12) × surface area × 7.48. <50 GPD minor, >200 GPD major.05
Worked through
A worked example: pool drops 0.5", bucket drops 0.25" over 24 hrs, 500 sq ft
- Net leak = 0.5 − 0.25 = 0.25 in
- Leak/day = (0.25 ÷ 12) × 500 × 7.48 = 78 gal
- 78 GPD = moderate leak
| Net drop /24hr | 300 ft² | 500 ft² | 700 ft² | Severity |
|---|---|---|---|---|
| 0.0625 in | 12 gal | 19 gal | 27 gal | Minor |
| 0.125 in | 23 gal | 39 gal | 55 gal | Minor |
| 0.25 in | 47 gal | 78 gal | 109 gal | Moderate |
| 0.5 in | 94 gal | 156 gal | 218 gal | Major |
| 0.75 in | 140 gal | 234 gal | 327 gal | Major |
06
Why it matters
How the result supports the next decision
Run the test with the pump off and the pool full, in calm weather, for 24 hours.
Place the bucket on a pool step, weighted, with its water level matched to the pool.
07
Good inputs
Improve the estimate before relying on it
- Run the test with the pump off and the pool full, in calm weather, for 24 hours.
- Place the bucket on a pool step, weighted, with its water level matched to the pool.
- If pool and bucket drop equally, your loss is evaporation, not a leak.
- Do one test with the pump on and one off — a difference points to a plumbing leak.
- Mark both water lines with tape for an accurate, easy-to-read measurement.
08
The boundary
How to interpret the result
Measurements, equipment specifications, site conditions and local requirements can change the practical result.
The engine reports invalid inputs and safety warnings beside the result. Resolve those messages before using the estimate.
09
Before acting
What should override this estimate?
- Measured site conditions and current test results
- Product labels and manufacturer specifications
- Qualified-professional advice and applicable local codes
10
Common questions
Frequently asked questions
How does the bucket test work?
You float or sit a bucket of pool water on a step so its surface matches the pool's, then mark both water lines and wait about 24 hours. The bucket loses water only to evaporation. If the pool drops more than the bucket, that extra loss is a leak. Equal drops mean evaporation alone.
How do I know if my pool has a leak?
Run the bucket test. If after 24 hours the pool's water line has fallen noticeably more than the bucket's, you have a leak — the difference is the leak amount. If they fell by about the same, your loss is normal evaporation. This simple comparison cancels out weather, which affects both equally.
How much water loss indicates a leak?
After accounting for evaporation via the bucket, any consistent extra loss is a leak. As a rough severity guide, under 50 gallons a day is minor, 50 to 200 is moderate, and over 200 gallons a day is a major leak needing prompt attention. Even small leaks waste water and chemicals over time.
Should I run the bucket test with the pump on or off?
Do both. A test with the pump running pressurizes the return plumbing, while a test with it off does not. If you lose more water pump-on, the leak is likely on the pressure side; if more is lost pump-off, it may be in the structure or suction side. Comparing the two narrows the location.
What conditions give the most accurate bucket test?
Calm, stable weather over a full 24 hours, with the pool filled to normal level and no swimmers. Wind and rain skew results, and splash-out adds false loss. Matching the bucket water level to the pool and keeping it shaded similarly to the pool surface improves accuracy.
How do you do a bucket test on a pool?
Sit a bucket of pool water on a step matching the pool level, mark both lines, wait 24 hours, and compare the drops.
How much water loss is a pool leak?
Any loss beyond what the bucket (evaporation) shows; under 50 GPD is minor, over 200 GPD is major.
Will a bucket test detect a small leak?
Yes — over 24 hours even a small leak shows as the pool dropping more than the bucket.
Primary sources
Use the result with current guidance.
These official references support safe planning context. Product labels, local requirements and qualified-professional advice take priority over a general calculator estimate.