How Much Water Does My Pool Need?

An empty vinyl liner pool under construction by Legendary Escapes
An empty vinyl liner pool under construction by Legendary Escapes

Your pool needs enough water to function properly. By this we mean that your system should have adequate water flow running from your skimmer and main drain into your system for filtration, and back into your pool.

You can isolate the main drain or the skimmer from the system and turn them off if your plumbing and valves allow this option. This can be nice when you are opening the pool in the spring. If your water level is not up to the level needed to operate your skimmer, you can turn the skimmer to the closed position and still run the main drain and the returns.

We have seen many many systems over the years that are troublesome. The most important thing for your plumbing system to be is easy to operate. If you have water coming in through the main drain and skimmer into your pump, you need to have water returning to your pool.

The correct operating level for your water at the skimmer will vary depending on your pool set up. As a general rule, you need enough water in the pool so when water is drawn through the skimmer you don’t create a whirlpool or suck air into the pipe. Sometimes a pool looks full, but when the pump starts pulling water through the skimmer it is pulling so fast the skimmer can’t refill fast enough. If you get any hissing, gurgling, or sucking noises from your skimmer, chances are something is obstructing the water flow, or you don’t have enough water in the skimmer. The water level should also be just low enough that debris such as floating leaves can pass under the upper level of the skimmer so that it can be caught in the skimmer basket. You will want to learn the normal operating level from your pool. If you are not sure, call your pool professional, we are happy to advise you of this level as well.

Monitor your pool water level daily. Add water if it appears to be too low. Some water will evaporate. Some may be splashed out during the pool’s use. If you have backwashed your system, or vacuumed on waste, you will have wasted some water from the pool. You typically have a few inches of water in the skimmer as leeway, so you don’t or shouldn’t have to fill the pool every day. If you are filling your pool every day, or noticing a half inch to an inch of water loss a day chances are you have a leak or some other issue that should be looked into.

A pool water volume will vary based on the size and shape of the pool. The formula to compute how much water your pool has is as follows:

For a rectangle pool multiply your length times width time average depth times 7.5

For a freeform, round, or oval pool, multiply your length times width times average depth times 5.9

With a freeform pool, some estimation is to be expected, and you may not have an exact water volume. You need to know the volume of your water for your chemical testing and balancing.

A pool under construction often looks much bigger or smaller than when it is full of water depending on your perspective. It’s always interesting to see!

If you hire a water truck to fill your pool when it is newly installed, you will also have an idea how much water is in your pool. Trucks vary in the load they carry, ranging from small loads of about 5,000 gallons per truck, to some of the larger residental trucks carrying 9,000 gallons of water. When we do a vinyl liner replacement or a gunite renovation, typically we ask the homeowner to bring in a truck load or two, or sometimes three, of water to get the pool full quickly. In instances where water quality is an issue, in areas of , high iron or other mineral content, having water brought in by truck is also an excellent idea. If you are in the Michigan area within the Milford service area, Legendary Escapes recommends Dave with Aqua Fill ( you can find his number in our service partners resource directory.)