The average 21-foot round pool with a depth of 48 inches holds 13,500 gallons of water. A 21-foot round pool with a depth of 52 inches holds 14,500 gallons, according to Robelle.
A 24-foot-round, 52-inch-deep pool holds a rounded 14,715 gallons of water if it is filled to the brim, or about 13,594 gallons if it is filled to an average depth of 48 inches. Most pools are not filled to the brim.
A 15 x 30-foot oval pool with an average depth of 48 inches holds 12,000 gallons of water. A pool with the same exterior dimensions and an average depth of 52 inches holds 14,800 gallons of water.
A 20-by-40-feet pool with an average depth of 5 feet holds 21,600 gallons of water. The same shape pool with an average depth of 6 feet holds 36,000 gallons.
To figure out how many gallons of water a pool holds, calculate the surface area and multiply by the depth of the pool to obtain a figure for the cubic volume. Multiply the cubic volume by 7.5 for a square or rectangular...
A pool with 10,000 gallons of water requires one or two 3-inch chlorine tablets per week to maintain the recommended 1 to 3 parts per million. Test pool water regularly, and adjust the amount of chlorine as needed.
The amount of gallons of water in a pool varies greatly depending on the size of the pool. The average in-ground backyard pool holds between 18,000 and 20,000 gallons of water.