Expert Verified Updated: March 2026

Pool Water Evaporation Rate Calculator

Calculate how many inches of water your pool loses to evaporation per day based on air temperature, humidity, and wind speed.

Is My Pool Leaking?

The "Bucket Test" is the gold standard for leak detection. However, knowing the theoretical evaporation rate helps you decide if a bucket test is even necessary. On a hot, dry day, it is normal to lose **1/4 to 1/2 inch** of water.

Pro Tip: Wind is the biggest "invisible" factor. Doubling wind speed can quadruple evaporation loss. Use a Solar Cover to stop 90% of evaporation instantly.

Actionable Steps

Factors of Evaporation

  • Temp Delta: The larger the gap between water and air temp, the faster the loss.
  • Humidity: Dry air acts like a sponge for pool water. High humidity slows loss down.
  • Wind: Air movement strips the saturated layer above the water, allowing more water to escape.

Pro-Tip

Wind is the biggest "invisible" factor. Doubling wind speed can quadruple evaporation loss. Use a Solar Cover to stop 90% of evaporation instantly.

Frequently Asked Questions

What is the bucket test?

Fill a bucket with pool water and set it on the first step of the pool. Mark the water level inside and outside the bucket. After 24 hours, if the pool level dropped more than the bucket level, you have a leak.

Can evaporation happen at night?

Yes, and often faster than during the day if the air temp drops significantly below the water temp (common in autumn/spring).

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