Calculating Pool Water Volume and MakeUp Water
The volume of a rectangular pool can be calculated using the following
formula:
Volume = Length x Width x Depth (average)

If the pool floor slopes uniformly from end to end, the average depth can
be found by adding the deepest and shallowest depth measurements and
dividing the results by two. If the pool's dimensions are in feet, the
volume will be in cubic feet. One cubic foot of water equals 7.5 gallons.
Example: The water volume of a pool 60 ft. long, 30 ft. wide and that
slopes in depth from 3 ft. to 10 ft. is as follows:
30 x 60 x ((10 + 3)/2) = 11,700 cubic ft. of water
11,700 x 7.5 = 87,750 gallons
Calculating MakeUp Water:
It is helpful to be able to calculate the amount of makeup water that needs to
be added to make up for water lose through filter backwashing, splashout,
evaporation or leaks. To do so, determine the number of inches of water depth
required to fill the pool and your pool's surface area (length x width) and
supplement them into the following formula:
Inches of Water x Pool Surface Area (sq. ft.) x .625 = Gallons of Water
