Evaporation vs. leak calculator
You're losing roughly 561 gallons (0.29 in/day). That's within normal evaporation range for a warm, dry, or windy week.
The bucket test settles it: a bucket of pool water on the top step loses water to evaporation at the same rate as the pool. If the pool drops faster than the bucket, that difference is a leak.
Losing water and not sure if it's evaporation or a leak? The calculator above helps you tell the difference, so you don't panic over normal loss or ignore a real leak. It centers on the classic bucket-test logic.
Normal loss vs a leak
All pools lose water to evaporation — often a notable amount per week in hot, dry, or windy weather, and more if the pool is uncovered or heated. That's normal. A leak is water escaping through the shell or plumbing, and it shows up as loss beyond what evaporation explains. The calculator uses your conditions to estimate expected evaporation so you have a baseline to compare your actual loss against.
The bucket test
The definitive check is simple. Fill a bucket with pool water, set it on a step so it's partly submerged, mark the water level inside the bucket and the pool level outside, and wait a day or two with the pump running normally. Evaporation affects both equally, so if the pool has dropped more than the bucket, you likely have a leak; if they match, it's just evaporation. The calculator's estimate complements this real-world test.
What to do next
Match your response to the finding. If loss matches expected evaporation, the fix is a cover — it cuts evaporation dramatically and saves water, heat, and chemicals. If loss clearly exceeds evaporation, investigate for a leak: check equipment and fittings for drips, watch whether loss changes with the pump on versus off (equipment-side vs shell), and call a leak-detection pro if you can't find it. Catching a real leak early saves water and prevents structural damage.
Frequently asked questions
How much pool water loss is evaporation?
It depends on sun, wind, humidity, water temperature, air temperature, and cover use. The best first check is to measure daily water loss and compare the pool against a bucket test.
How does a pool evaporation calculator work?
It estimates gallons lost by multiplying pool surface area by water-level drop. One inch of water over one square foot is about 0.623 gallons.
How do I know if my pool has a leak?
Run a bucket test. If the pool level drops more than the water inside the bucket under the same conditions, a leak is more likely than simple evaporation.
Can a pool cover reduce evaporation?
Yes. EPA WaterSense says pool covers can prevent up to 95 percent of pool water evaporation when used properly.
Should I add water before testing for a leak?
Bring the pool to its normal operating level before testing, then turn off autofill if you have it. Mark water levels clearly and compare after 24 hours.
Embed this calculator (free)
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