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The Main Causes of Pool Water Evaporation

Did you know that swimming pools lose about a quarter of an inch of water each day? Additionally, variations in wind intensity, humidity and sunlight can drastically increase these water loss rates.

You may look at your pool at some point and notice that the water level looks lower than usual. What could be the issue? More than likely, this is the result of pool evaporation. But how can you be so sure? We’ve compiled a list of water evaporation causes that you might find helpful in determining the cause of your pool water loss — as well as a helpful way to keep the water inside your pool from disappearing.

The most common causes of pool water evaporation include:

lack of humidity can contribute to pool water evaporation

Lack of Humidity

exposure to sunlight can cause water evaporation

Exposure to Sunlight

high temps can lead to evaporation

High Temperatures

water splash out can cause pool water loss

Water Splash Out

Lack of Humidity

If you happen to live in an area where there is little to no humidity, water evaporation would be the main cause of water loss. Here’s how evaporation works. Evaporation can be compared to that of a sponge. The drier the heat, the more water is absorbed. An environment with higher humidity will lose less water. An environment with lower humidity will result in water evaporation.

Exposure to Sunlight

Is your pool situated somewhere where direct sunlight hits? A fully exposed pool means more water evaporation. Unscreened pools will lose more than a screened pool. However, we don’t expect all pool owners to build a pool enclosure as this an expensive add-on, but keep in mind that fences, structures, even trees near the location of a pool helps lower the amount of evaporation that occurs in pools.


Temperatures at 100℉? A summer’s intense heat can be a huge contributor to the water loss in your pool. The intense heat during the day mixed with the cooler weather at night is the perfect recipe for evaporation. Here’s an easy explanation on why this water evaporation occurs. The difference in temperature between your pool water and the outside air is what causes evaporation. Imagine your pool as a pot of water on the stove; as the water starts to heat up, contact with air causes steam, which causes evaporation to occur.

Splash Out

While this is not a direct cause of water evaporation, we must not forget that simply using the pool itself can cause water loss. Think about it. Splash out occurs when swimmers enter and leave your pool, especially if these swimmers are diving in, doing cannonballs, and even playing water games. You’d be surprised at how much water loss is caused over the course of one day.

Want to Decrease Water Evaporation? Try a Solar Cover!

We understand that the factors that cause evaporation are not entirely controllable, but there is definitely a way to decrease water evaporation. A solar cover is a great way to shield pool water and decrease water evaporation. In fact, a solar cover can reduce water evaporation up to 95% when used regularly.

Top Products

Solar Pool Covers

Solar Covers

Variable Speed Pool Pumps

VS Pumps

Cartridge Filters

Cartridge Filter

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Leslie’s makes every effort to provide accurate recommendations based upon current ANSI/APSP/ICC-5 2011 (R2022) standards, but codes and regulations change, and Leslie’s assumes no liability for any omissions or errors in this article or the outcome of any project. You must always exercise reasonable caution, carefully read the label on all products, follow all product directions, follow any current codes and regulations that may apply, and consult with a licensed professional if in doubt about any procedures. Leslie’s assumes no legal responsibility for your reliance or interpretation of the data contained herein, and makes no representations or warranties of any kind concerning the quality, safety, or suitability of the information, whether express or implied, including, without limitation, any implied warranties of merchantability or fitness for a particular purpose.