Evaporation Index

Pool evaporation is effected by a variety of weather and pool related variables.

The Evaporation Index Calculator provides a single representative number from these variables which allows you to predict the evaporation rate at a particular pool on a particular day.

Using the Calculator

Enter your zip code in the box to automatically populate the current weather related information for your area. You can also enter weather related variables directly into the data boxes if you wish. Pool related variables are automatically populated with “typical” values although these also can be changed to best represent a particular pool. Our typical pool assumes a water temperature of 85° F and a solid fence or natural wind break surrounding the pool at about 20 feet from the pool edge. We also assume normal circulatory operation of a pool with no fountains, waterfalls or spillways.

Once you have the correct variables entered press the “calculate” button.

(Click “Calculate” each time you enter or change values above.)

What Does the Index Number Mean?

While the Evaporation Index is just a number intended for comparing relative results from day to day and season to season it is possible to translate the index into an estimated rate of loss in inches or centimeters.  The Index represents 20 times what the water loss in inches would be in a “typical” pool if these weather variables remained constant for a period of 24 hours, (this is about 8 times the amount of water loss in centimeters).

For instance, an Index of 4.4 would translate into an estimated rate of .22 inches of evaporation per day.

Index of 4.4 / conversion factor of 20 = .22″ ( or 4.4 / 8 = .55cm) of water lost to evaporation in 24 hours.

Other Tips

Trying modifying different variables to see how they affect the evaporation index number.

Keep in mind that the index is utilizing instantaneous weather conditions and that those conditions may not be consistent over an actual 24 hour period.  Wind is a very big factor in this calculation, and it is generally weaker at night than it is during the day. As a result, the index as measured during the day may indicate a larger water loss than what would actually be experienced in an actual 24 hour period.

We hope that you find the Evaporation Index Calculator to be another valuable tool for providing professional leak detection and repair service to your customers. Please contact us with questions or comments.