# How Many Gallons of Water in a 21 Foot Round Pool

How Many Gallons of Water in a 21 Foot Round Pool?

If you are a proud owner of a 21-foot round pool or considering purchasing one, you might be wondering how many gallons of water it holds. Knowing the capacity of your pool is essential for maintenance, chemical treatment, and determining the appropriate amount of water required to fill it. So, let’s dive in and find out how many gallons of water your 21-foot round pool can hold.

The capacity of a pool is determined by its shape and size. In the case of a round pool, you can calculate its capacity using a simple formula. The formula to calculate the gallons of water in a round pool is:

Capacity (in gallons) = 5.9 x radius^2 x average depth

For a 21-foot round pool, the radius would be half of the diameter, which is 10.5 feet. Let’s assume an average depth of 4 feet. Plugging these values into the formula, we get:

Capacity = 5.9 x (10.5)^2 x 4
= 5.9 x 110.25 x 4
= 2598.9 gallons

Therefore, a 21-foot round pool can hold approximately 2599 gallons of water.

Now, let’s address some common questions related to pool capacity:

1. How long does it take to fill a 21-foot round pool?
The time required to fill a pool depends on the water flow rate. On average, it could take several hours to fill a pool of this size.

2. How much does it cost to fill a 21-foot round pool?
The cost of filling a pool depends on the local water rates. For an estimate, you can multiply the number of gallons by the cost per gallon in your area.

3. Can I use well water to fill my pool?
Yes, well water can be used, but it might require additional treatment and testing.

4. How often should I change the water in my pool?
It is generally not necessary to change the water unless there are specific issues or concerns.

5. How do I maintain the water quality in my pool?
Regular testing, balancing chemicals, and proper filtration are essential for maintaining water quality.

6. Can I use a pool cover to reduce evaporation?
Yes, using a pool cover can help reduce evaporation and conserve water.

7. How do I calculate the average depth of my pool?
Measure the depth at several points and calculate the average.

8. How often should I check the water level?
Regularly check the water level and maintain it within the recommended range.

9. How much chlorine do I need for a 21-foot round pool?
The necessary amount of chlorine depends on the pool size, usage, and other factors. Follow the manufacturer’s instructions or consult a pool professional.

10. Can I use rainwater to top off my pool?
Yes, rainwater can be used to top off the pool, but it should be properly treated.

11. How should I drain my pool?
If necessary, consult local regulations and consider professional assistance to drain your pool safely.

Knowing the capacity of your 21-foot round pool is crucial for its proper maintenance and enjoyment. With this information, you can now confidently plan for filling, treating, and managing your pool to create a refreshing oasis in your backyard.