Pool owner looking for a way to find a leak in his swimming pool

How to find a leak in a swimming pool

Is your pool leaking? Ouch, that’s probably not good. But it might not be all that bad, either. A pool leak can be caused by a number of different things. Some are quicker and cheaper to fix than others. 

Here, we’ll help you find that leak, as well as where to get pool leak repairs here in NZ.

In this guide to find a leak in a swimming pool:

How to find a leak in a pool?

Remember that pools will naturally lose a little water through splash-outs and evaporation, and gain some if exposed to rain. But if you need to replace more than a couple of inches of water in your pool every week, you probably have a leak. 

And it’s important that you don’t just replace that water.  You need to find the leak and fix it to protect other parts of your pool from degrading or breaking down. 

Here are some tips for how to find it. 

The most common places to find leaks in a pool

First thing’s first: where are swimming pool leaks most common? Use this list to prioritise your leaking swimming pool detection tests and eliminate each as you go.

The most common areas that you might find a leak:

You might be wondering whether the type of pool you own is likely to impact where you get a leak. The truth is, not really. The structure and equipment of above and inground pools is very similar. 

But there are a couple of key things to know about each. So let’s cover those now. 

Inground pool leak detection

Leaks can occur in similar places regardless of whether you have an inground or above ground poolBut inground pools can be harder to repair for obvious reasons. 

The best way to avoid unnecessary costly repairs to your inground pool is to try everything else yourself first. Hopefully your leak is coming from the skimmer or something easy to fix.

Above ground pool leak detection

One disadvantage of an above ground pool is its exposed walls. These are commonly made from thin vinyl, which can be damaged quite easily with sharp objects or worn down by pool chemicals

If the location of the leak in your above ground pool isn’t obvious, you can use the bucket test and dye test that we discuss later in this article. 

If you find a tear in the pool wall, you can use vinyl patches to cover it up. If these don’t do the trick, you may need to drain the pool and have it repaired by a professional.

Leaky pool plumbing

If your pool is losing more water than it should through evaporation alone, there might be a plumbing issue. If there’s a crack in the filter’s plumbing, this will be hard for you to reach. And you’ll need to get professional help.

So it’s a good idea to check for this first to save time. You can have a look at:

If you can’t see any obvious issues, then you need to perform some leaking swimming pool detection tests. Keep scrolling for the bucket test and pool leak dye test. There could still be plumbing issues but they might be hidden under your pool. 

How to find a leak in swimming pool plumbing

Try switching off the system and checking for leaks. If there’s still water escaping, it’s unlikely to be a pipe issue. 

If the leak did stop, you can test the individual pool lines to find out where the leak is coming from. You can use a pressure testing rig to do this.

Or if you’d rather have professional help, an expert can use a specialised device to locate the exact spot of the leak. They add air to the pipe and listen for the air escaping with headphones, pinpointing exactly where the problem is. 

The good news is that you can often fix these issues with minimal impact on the rest of the plumbing. It’s rare that you need to replace all of it.

Pool leak detection

Here are two quick, easy and low-cost ways to determine whether your pool is leaking.

The bucket test

All you’ll need is a bucket and a waterproof marker or tape. Here’s what to do:

  1. Place your empty bucket on the second step of your swimming pool. Fill it with water so that it matches the pool’s water level, and mark that inside the bucket. 
  2. Turn off the pool pump and any other automated systems you have activated in your pool.
  3. Wait a day, and then compare the water level with where you marked the bucket. Is there a difference? If the pool water is lower, there’s probably a leak. 

You can also use this same method to test for pump and plumbing leaks: In that case, repeat step one above, but keep the pump on now. Then, compare the results the next day. If you notice that even more water is gone with the added pressure from the pump, the leak is probably in your filter system or plumbing.

The pool leak dye test

Using pool leak dye, you’ll be able to find the exact location of the problem relatively easily. But you do need a rough idea of where you think the leak is already. 

For this process, you’ll need pool leak dye and waterproof tape. Here’s what to do:

  1. Try to find the leak first and narrow down the potential spots before using the dye. Check around the pool and its equipment for excess water.
  2. Turn off your pool pump and any accessories. The water needs to be as still as possible so that the dye doesn’t spread out everywhere. This also helps you find leaks in the skimmer.
  3. Go to the location in your pool where you think the leak is coming from. Without touching the water yourself, squirt the dye close to the surface and the pool wall. If the leak is close, you should see the dye pull towards it. 
  4. Repeat this step until you find the leak. If you think it might be at the bottom of your pool, you’ll need to dive down and try it under the water. Just make sure to be as still as you can.
  5. Mark the spot with waterproof tape or a waterproof marker. You’ll be able to find it easily when you’re ready to fix the leak. 

Pool pump leaks

Your pump keeps your water flowing and clean. So you want to fix any pump issues as soon as you can. Low water level can be a sign of pool pump leaks. Your water level should be a third to half way covering your skimmer. Any less and air can get in, causing an issue for your pump. 

There are a number of things that could be causing a leak in your pool pump. 

Where to find pool pump leaks

  • Leaks in the suction side: you probably won’t see these leaks when the pump is running because it will move fast through the pipes. When that pressure is off, the water will leak through. A tell-tale sign of suction side leaks is bubbles inside the pump or blowing out of the jets in the pool when it’s running. However, if you have an ozone system it’s normal to have bubbles coming back into the pool 
  • Leaks in the pressure side: if you can see drips from the discharge pipe, water under your pump, or if your pool water level is particularly low, these might signal pressure side leaks.
  • Pump lid and housing: check if the pool pump is leaking from the lid and any rubber o-rings underneath it. The lid should seal tightly and not have any cracks. There are also o-rings between the pump housing and the motor. If these are worn, they’ll need replacing. If these all look good, check the pump housing itself for cracks. 
  • Cracked pipes and valves: pour water over the pipes and valves and check for bubbles. 
  • Strainer basket: check the o-ring in the strainer basket. If this is damaged or not working, the seal is not tight enough. Simply replace the o-ring. 
  • Blocked impeller: if debris gets into the impeller, this can block or damage it. You might simply need to unblock it, or you may need to replace the impeller. 
  • Mechanical seal: this seal connects the impeller and motor. If it is damaged, water can get into the motor and stop it working properly. You’ll normally see a puddle or damp spot under the middle of the pump. If the seal has been leaking, water can get into the pump’s motor, which can cause the motor to sound strange. You may need to replace the shaft seal.
  • Discharge pipe: these pipes can be affected by ground movement, and the fittings attached can sometimes beak away. This can cause leaks – which can sometimes be difficult to find. 

Pool leak repair tips

If you need a minor pool leak fix that you can apply yourself, here are some of the common options to consider.

  • Waterproof tape: this can help you find a leak and mark it, to either keep track or repair it later on.
  • Vinyl patches: these can be used to block minor leaks in vinyl-liner pools, with patch kits available for slightly larger areas.
  • O-rings: these are designed to seal connections, so are often the cause of minor leaks. They’re usually cheap and easy to replace. 
  • Putty, epoxy, and sealant: these can be squeezed into cracks and seal leaks. 

If your leak is bigger than these fixes, you should probably get professional advice.

Swimming pool leak detection services

It can be costly to hire a professional for helping finding and repairing swimming pool leaks. But it’s worth getting the problem fixed as quickly as possible

If none of the DIY options have worked and you’d like expert help, you can find it with one of our trusted suppliers. See our NZ pool dealer directory here.

About the author
Adrian Hill
Adrian Hill

Hey! I'm Adrian, founder and pool expert here at Dolphin Pacific. I love spending time with family, fishing, and have been known to brew my own beer.

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