Determining the amount of water an oval pool holds requires some simple calculations based on the pool’s dimensions. An oval pool that is 15 feet wide and 30 feet long can hold a significant amount of water, but the exact volume depends on the pool’s depth.
Calculating the Volume of an Oval Pool
The basic formula for calculating the volume of an oval shaped pool is:
Volume = Length x Width x Average Depth x 7.5
Where:
- Length is the longest measurement across the center of the pool
- Width is the shortest measurement across the center of the pool
- Average Depth is the average depth across the entire pool
- 7.5 is a conversion factor to calculate gallons
For a 15 x 30 oval pool:
- Length = 30 feet
- Width = 15 feet
The average depth of most in-ground oval pools ranges from 3.5 feet to 8 feet deep. For this example, let’s assume the pool has an average depth of 5 feet.
Plugging these measurements into the formula:
Volume = 30 x 15 x 5 x 7.5
= 33,750 gallons
So an oval pool that is 15 feet wide, 30 feet long, and has an average depth of 5 feet will hold approximately 33,750 gallons of water.
Estimating Average Depth
The above calculation assumes the pool has an even depth of 5 feet across its entire length and width. However, most oval pools have sloped sides that are deeper in the center and more shallow at the ends. Finding the true average depth requires a more detailed calculation.
A quick way to estimate average depth is to take measurements at various points along the pool floor and walls. Measure the shallowest and deepest parts, then take 2-3 more measurements in between. Add up all the measurements, then divide by the total number to find the approximate average depth.
For example, for a pool that has:
- 3 feet deep at the shallow end
- 8 feet deep at the deepest part
- 5 feet deep halfway along the length
- 4 feet deep a quarter of the way along the length
The total of these 4 measurements is 3 + 8 + 5 + 4 = 20 feet.
Dividing by the number of measurements (4) gives an average depth of 5 feet.
Accounting for Round Corners
One complexity with oval pools is accounting for their rounded corners. An oval shape has two semicircular ends joined by straight sections along the sides. This means the pool may be slightly longer when measured across the rounded parts versus just the straight sections.
To handle this, you can either:
- Take the length measurement across the center of the straight sections only
- Take the max length measurement including the curved corners
Using the straight length only will give a slightly more conservative estimate for total gallons. But measuring over the curves will be more accurate. Just be consistent in whichever method you use when calculating the volume.
Other Factors That Affect Volume
A few other things to keep in mind that can impact the overall water volume:
- Shape irregularities: Oval pools often have slightly uneven shapes that make calculating the volume more difficult.
- Sloped walls: In addition to sloped floors, some pools have angled rather than vertical walls which affects depth.
- Steps and benches: Built-in pool elements like stairs, benches, and swim-outs take up space and decrease the total water capacity.
Small irregularities like these are difficult to account for in volume calculations. The most accurate way to determine the exact pool volume is to multiply the surface area by the average depth. But this requires more complex measurements and math.
For a rough estimate, the basic oval pool formula provides a good approximation in most cases. Just keep in mind your calculation may be off by 5-10% depending on the pool’s specific shape and features.
Volume Tables for Common Oval Pool Sizes
To make it easier, here are some common oval pool dimensions with estimated volumes based on an average 5 foot depth:
| Pool Size (Length x Width) | Approximate Volume (Gallons) |
|---|---|
| 12 x 24 oval | 22,500 |
| 15 x 30 oval | 33,750 |
| 18 x 33 oval | 59,625 |
| 18 x 36 oval | 63,000 |
You can use these numbers as a baseline for comparing pools of standard dimensions. Just keep in mind the volume may vary depending on the specific shape and depth of your pool.
How Many Gallons Does My Oval Pool Hold?
Now that you understand the basics of calculating oval pool volumes, here is a summary of the process:
- Measure the length and width of the pool across the center.
- Determine the average depth by taking multiple depth readings.
- Plug the dimensions into the oval pool volume formula.
- Double check your measurements and math to ensure accuracy.
- Adjust the calculation to account for any irregular shape or unique features.
This will provide an estimated volume that you can use to determine how much water is needed to fill the pool. Keep in mind that some loss will occur due to splash out, so add an extra 5-10% to the volume when filling.
Understanding your pool’s capacity is also helpful for adding chemicals properly and determining flow rates for pumps and filters. Refer to the volume whenever maintenance requires precise water measurements for best results.
Tips for Measuring Oval Pool Dimensions
Getting accurate measurements is crucial for determining the correct water volume. Here are some tips for measuring oval pools:
- Use a long, straight tape measure that can span the entire length and width.
- Measure across the center of the pool, not around the outer edges which may be uneven.
- Have two people take measurements – one at each end to straighten the tape.
- Check width in two places at the rounded ends and straight middle and average.
- For depth, take readings at the shallow and deep ends, then 2-3 more spaced evenly.
- Mark measurements directly on the pool deck or wall, and double check for accuracy.
With precise measurements, you’ll get the closest approximation of your oval pool’s volume. Rounding up on dimensions is better than rounding down to ensure you have enough water to fill it.
Alternative Ways to Determine Pool Volume
If you want to skip the measurements and calculations, there are a couple alternative options for determining the amount of water in your oval pool:
- Lookup pool volume charts: Some pool manufacturers provide volume charts listing capacities for their standard oval pool models. Find the closest match to get an estimate.
- Use a pool volume calculator: Input your dimensions into an online pool volume calculator to instantly get the volume.
- Contact the pool installer: The company or contractor that installed your oval pool may have the exact volume amount on record.
However, the most accurate way is still to manually measure and calculate it yourself. So take the time to carefully determine your pool’s unique length, width, and average depth.
Filling an Oval Pool with Water
Once you know the approximate volume of water needed, you can start filling the pool. Some tips for filling an oval pool include:
- Make sure the surrounding ground is properly graded for drainage and there are no leaks.
- Fill slowly and evenly around the entire perimeter to prevent structural damage.
- Don’t fill higher than the tile line if the concrete hasn’t fully cured.
- Attach a hose to a nearby spigot or use a portable water tank for filling.
- Add chemicals like chlorine once the water reaches the appropriate level.
- Visually check that the water level is even on all sides.
Filling an average 15 x 30 oval can take 12 hours or longer depending on your water pressure. So be patient and take care to prevent overfilling parts of the pool during the process. Once full, your freshwater oval pool is ready for swimming!
Maintenance Considerations for Oval Pools
Caring for an oval pool is similar to other pool shapes, but the curved ends and varied depths require some unique maintenance considerations:
- Use pool brushes with telescoping poles that can reach the rounded corners.
- Vacuum carefully around steps and other sloped areas.
- Add chemicals gradually and circulate thoroughly to account for uneven distribution.
- Inspect the center depth for accumulation of debris which is harder to reach.
- Drain from the deeper areas first when lowering the water level.
Knowing the exact water volume also helps with maintenance tasks like adding the proper chemical doses. Be sure to record your oval pool’s dimensions and volume for easy reference year after year.
Conclusion
Calculating the amount of water held in an oval swimming pool requires measuring the length, width, and average depth, then using a simple formula to determine the approximate volume. Allow extra capacity for displacement and splashing when filling the pool. Knowledge of your pool’s dimensions is also extremely helpful for ongoing maintenance needs. With a little bit of measuring and math, you can find out the gallons required for your oval pool.
