How Much Water to Fill My Pool?

Do you ever wonder how many gallons of water it would take to fill a medium size above- or below-ground swimming pool?  If you are similar to the average person, you have likely thought about it once or twice in your lifetime, but probably not much more than that.  Perhaps during one of your famous cannonball dives and several gallons are displaced out of the pool, you may have thought about it, in a competitive way!

The formula is fairly simple, especially if you are familiar with a few Math terms.  Let's look at a couple examples.

1.) How many gallons of water does it take to fill a circular swimming pool that measures 20ft across and has an average water depth of 5ft?
Solution:
* Find the area of the surface, which = Pi (3.14) x Radius squared.
3.14 x 24 x 24 = 576 sq.ft.
* Find the volume of the pool by multiplying the top surface area times the depth of the pool, which is 5 ft.
576 sq.ft  x 5ft = 2880 cubic ft.
* Knowing that there are approximately 7.5 gallons of water per cubic foot, you can multiply the volume times the number of gallons of cubic feet to know how many gallons you need.2880 cubic ft.  x  7.5 gallons per cubic ft. = 21,600 gallons!


Take a look at another example, this time the pool is rectangular shape, and measures 16ft x 36ft and is 5ft deep throughout the pool.  How much water does it take to fill the pool?
Solution:
* Find the area of the surface which is 16 x 36 = 576
* Find the volume of the pool by multiplying the top surface area  x  the depth, which is 576 x 5 = 2880 cubic ft.
* Multiply the volume  x 7.5, which is 2880 x 7.5 = 21.600 gallons!

Did you notice something?  Both pools with different shapes and different dimensions require the same number of gallons to be filled!  Next time you are trying to decide which pool to build at your new home, you will know that there is more than one shape of a pool that can have the same overall dimensions and water usage!

For those of you who want to know how many Liters it would take to fill the pools in our examples, you can simply multiply 21,600 gallons x 3.78 L per gallon.  It would take 81,648 L to fill each pool! 

Happy swimming, everyone!