How much water should a pool lose in April?

Answer 1

The National Weather Service uses a large water pan with a diameter of 4 feet. They measure the drop in water level in one day, fill it back to the level it was before and measure the level drop the next day. They and others do this all over the United States. Others do it throughout the world. The Weather Service reports the evaporation at each location, each day, and sum all these daily values up to obtain an annual evaporation rate in inches. All the data through the US is collected and compiled into an annual evaporation map. Looking at the annual evaporation map one can find the average annual evaporation rate for any location. It is roughly 100 inches for Tucson, Arizona. The evaporation rate varies with temperature, wind speed, sunshine, and relative humidity. The evaporation rate also varies throughout the year. A rough daily rate is given by dividing the annual rate by 365 days. Rough daily evaporation rate = Annual Evaporation rate / 365 For Tucson the rough evaporation rate is 100 inches/365 which is about 1/3 inch per day. Swimming pool If we use this rough evaporation rate, we can find how much a swimming pool water level might drop in 5 days Total surface drop = (5 days) (daily evaporation rate)