How to Patch a Pool with Water in it

Aquaman Leak Detection Blog

The Best Method for Pool Water Loss Calculation

On Nov 6, 2017

Pool Water Loss Calculation.jpg

You may find that you are adding water to your pool or hot tub more frequently and you are not sure why. The loss of one inch or more of water each day will rapidly add up to gallons of wasted water.

Your first step is the bucket test. You need to conduct this test in an uncovered pool. Fill the bucket with water and compare the water level after the bucket has sat out overnight. The average rate of evaporation is about 1/4-inch per day. However, if your pool has lost more than 1/4-inch of water after the 24-hour test, you are likely to have a leak that accounts for the loss.

Did you know that different sized pools use different water loss calculations? Here are several formulas for pool water loss calculation based on the shape of your pool. You can also calculate the probable cost of the water loss based on your monthly bill.

Approximate Water Loss

A circular pool or spa tub that has a 10-foot diameter will lose about 49 gallons of water a day. A smaller round spa tub five feet across will lose about 12.49 gallons. This is the result of losing only one inch of water in 24 hours.

The formula for a 10' round spa pool losing 1.5 inches a day is:

 10' x 10' x 1.5" x .48929 = 73.29 gallons a day

The .48929 is derived from the average volume of the pool or tub when filled to the recommended level. Almost .49 or half of a gallon of water covers a one-foot diameter area one-inch deep in a round pool or spa tub. 

The rectangular pool that is 18'x36' loses about 404 gallons a day when the bucket test shows a one-inch drop in the water level. An 18'x36' pool with an average depth of five feet holds about 24,300 gallons or water. The loss of 400+ gallons of water a day is substantial even though the water level may only drop about an inch at a time.

The water loss calculation formula for a rectangular pool that measures 18'x32' losing two inches a day is:

   18' x 32' x 2" x .6233 = 718 gallons a day

It takes about .62 of a gallon of water to cover one square foot one-inch deep in a rectangular or square pool. Divide 718 by 24 and the pool is losing 29.91 or almost 30 gallons of water in an hour. This amount of water loss will saturate the deck and ground in a very short time.

You can also use the formula for water loss calculation in a rectangular pool for that of an oval pool based on its dimensions. The formula for a round pool could also apply to an oval. Freeform pools are more difficult to calculate, but these will give you a rough estimate.

The Cost

The average yard swimming pool holds 18,000 to 20,000 gallons based on its size, depth, and shape. Calculate the volume of water by multiplying the length by width by average depth by 7.5 for rectangular, square or freeform pools. Use the multiplier of 5.9 for a round or oval pool.

A rectangular pool approximately L30' x W16' x D5' x 7.5 = 18,000 gallons.

The cost to refill a smaller pool with 15,000 gallons can run about $80 to $100, based on where you live. Add the expense of extra chemicals to control the pH balance and keep the pool clean. A leak is expensive if you just keep refilling the pool.

Conserve water and save money by repairing leaks immediately. Aquaman Leak Detection will find and repair leaks in one visit. Aquaman serves Brevard County and all of Florida.

Swimming Pool Leak Water Loss Calculator


By Aquaman

We now proudly serve all of Florida. Each of our trained and certified pool leak detection specialists utilize the most advanced methods and technologies.

Blog Comments