Fountain Water Evaporation

Evaporation of fountain water by region

Confused about how often you should re-fill your fountain? There is no set guide to how much water will need to be added to a fountain, or how often. Many variables determine the evaporation rate of water. These may include the type of heating or cooling you use in your home, the size of the fountain, wind speed, and the climate you live in. The highest rates are typically found in arid regions of the country, particularly Arizona. Coastal areas with high humidity and cool weather, such as Maine, have comparably very low rates of evaporation.

This chart shows the rates of evaporation by inches per year, across the country (click the map to enlarge). The Geotechnical, Rock and Water Resources Library of Arizona has researched and provided information on evaporation which can help you determine how much water you will need to put in your fountain each day. For example, in Tucson, Arizona, the annual evaporation rate is 100 inches. Divide this by 365 days, and you get roughly 1/3 of an inch per day.

Outdoor fountains typically need to be refilled more often than indoor fountains, especially if they are in direct sunlight, although they may also receive rain water. A tabletop fountain kept indoors, in an area of relatively balanced humidity, will only need to have a cup or so of water added about every other day. Be sure to keep the water level covering the pump at all times, or you'll run the risk of burning out the motor. A good way to remember to re-fill your fountain water is to get in the habit of doing it at the same time you water your plants.

For more information on fountain water, you may be interested in Changing Your Fountain Water, Using Distilled Water in Your Fountain and Maintaining the Correct Water Capacity.

Source: Geotechnical, Rock and Water Resources Library of Arizona