Pool Water Evaporation Calculator
Estimate how much water your swimming pool loses to evaporation based on local environmental conditions.
Estimated Evaporation Results
Daily Loss (Gallons):
0
Weekly Loss (Gallons):
0
Daily Depth Loss (Inches):
0
Monthly Cost Estimate (approx. water rates):
$0.00
Understanding Pool Evaporation
Swimming pools naturally lose water through a process called evaporation. This occurs when liquid water changes into water vapor. While it might seem negligible day-to-day, a standard backyard pool can lose thousands of gallons per year, impacting your water bill and chemical balance.
The Factors That Drive Water Loss
Evaporation rates are not constant; they fluctuate based on four primary environmental factors:
- Temperature Differential: The difference between the water temperature and the air temperature. High water temperatures combined with lower air temperatures (common in heated pools at night) accelerate loss.
- Humidity: Dry air has a higher capacity to hold moisture than humid air. Pools in arid climates like Arizona evaporate much faster than those in Florida.
- Wind Speed: As wind blows across the water's surface, it carries away the saturated air layer directly above the water, replacing it with drier air that encourages more evaporation.
- Surface Area: The larger the surface area of the pool, the more space available for water molecules to escape.
Typical Evaporation Rates
A typical swimming pool loses about 1/4 inch of water per day on average. In extreme conditions—high heat, low humidity, and high winds—this can jump to 1/2 inch or more. If you are losing more than 2 inches per week, you should perform a "Bucket Test" to check for structural leaks.
How to Reduce Evaporation
The most effective way to combat evaporation is by using a solar cover or "pool blanket." Covers can reduce evaporation by up to 95%. Liquid solar covers are another option, though they are less effective in windy conditions.