Even if you’ve got one of the best pools around, sooner or later, you’re going to discover that your pool is in need of maintenance!
One of the most common issues that most pool owners find themselves having to deal with is losing water, and as we’re sure you already know, it can be pretty difficult to figure out what the issue is.
When it comes to pools, a variety of different factors could be at play when it comes to water loss, so if you’re noticing that your pool is losing water whenever you turn your pump off, then it’s important to check for mechanical issues, structural issues, plumbing problems and much more.
Though that might seem a little daunting – don’t panic, because we’re here to help you figure out why your pool may be losing water when the pump is off.
Below, not only are we going to be talking you through some potential reasons why your pool may be losing water, but we’ll also be talking you through some solutions to stop it from happening further.
From structural issues to plumbing problems – we’ve made sure to cover all bases, so that you can get to the bottom of your pool water loss as quickly as possible. So, whenever you’re ready – let’s dive straight in!

Why do pool leaks occur?
So, as you might have already guessed, there isn’t a “one size fits all” approach to getting to the bottom of what might be causing your pool to lose water every time that you turn the pump off. Even though we wish that we could say there was, as we’ve already mentioned above, a variety of factors can contribute to water loss in a pool, including the following:
- Mechanical issues
- Structural issues
- Plumbing problems
- Age
- Broken fittings
- Damaged pipes
Why is my pool losing water when the pump is turned off?
One of the first reasons that your pool may be losing water when the pump is turned off is due to mechanical issues.
If you’re noticing that your pool is losing water (regardless of whether the pump is on or off) we’re recommending that you take the time to check the automatic fill device on your pool if you have one, as this can make it very hard to detect what the cause of a pool leak is.
If you’re noticing a green algae forming in your pool alongside water loss, then this could be a sign that you have a pool leakage problem.
In addition, if you happen to have a vinyl pool, we recommend that you double-check your pool skimmer. The most clear indication that your skimmer is damaged or leaking is the water inside your skimmer dropping to the bottom of the skimmer while it is in use.
Usually, a leak inside the skimmer can only be noticed when the pump has been turned off, and this can be a reason as to why you’re noticing that your pool is losing water whenever you turn your pump off.
If you find that this isn’t the case, then another reason why you may be noticing that your pool is leaking when you turn your pump off is because of a leak in your skimmer pipe.
If you do have a leak inside your skimmer pipe, then one of the biggest indications of one is your pool leaking more when the pump has been turned off, as when the pump is on it can create a vacuum that prevents less water from escaping.
If the skimmer pipe isn’t what’s causing your pool to lose water whenever you turn your pump off, then another reason as to why you may be noticing that your pool is losing water is due to the main drain.
The main drain can be one of the most difficult areas of the pool to detect a leak, as it can only be inspected when the pool has been totally drained. If your main drain does happen to have a leak, then there is a chance that switching off your pump could cause its leak to become worse.
The main reason for this is simply due to the way that the main drain can develop rust in the hydrostatic relief valve and render it ineffective, so when the pump is turned off, water can then begin to leak out of the pipe.
How do I fix the leak in my pool?
Even though there are a variety of different reasons as to why you might be finding that your pool is leaking when you turn the pump off, it’s very important to make sure that you get the leak fixed as soon as you can – otherwise you might find yourself having to fork out hundreds (or potentially even thousands) of dollars on repair costs.
For this reason, unless you are confident in your ability to both identify and correct leakages in our pool, we strongly recommend that you hire the help of a professional who will be able to do the job for you.
The last thing that you want to happen is to have to spend way more than you initially thought on fixing your pool from an accidental mishap on your end, which is why we recommend that you play it safe and go with a professional.
Besides making sure that you are getting your pool leak fixed as quickly as you can, you should also ensure that you are regularly checking for any telltale signs of a pool leak, as they can quite easily become uncontrollable, which will, in turn, lead to you having to deal with even more damage to your pool.
Why not schedule annual maintenance checks by a professional? That way, you’ll be able to catch leaks in their early stages.