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The Complete Guide to Pool Leak Detection

Have you noticed your pool starting to lose more water than normal? It could be different weather conditions causing more evaporation than usual, or it could be a minor leak.

Either way, we’re here to give you a few ways to find out for sure and how to fix any potential problems.

Top Areas Prone to Leaks

Pool leaks can happen through several areas, so figuring out where yours is coming from can take some time. But these three top spots are a good place to start.

Skimmer Leaks

The most common area for pool leaks is around the skimmer. Where the skimmer meets the pool surface, it often separates more than it should and allows water to seep out.

This gap can be caused by small debris that gets caught in between or in a small skimmer crack. Or it can be caused by normal concrete expansion from age and weather. And in some cases, it can simply be caused by a loose faceplate.

Light Leaks

Another common area for leaks is around the lights in inground pools. These can happen the same way skimmer leaks do.

Many times, the conduit pipe will separate from its niche. This will usually lead to a slow leak so it’s something to check out.

Plumbing Leaks

Occasionally, you’ll have a leak in the underground plumbing. Usually, though, the pipes that leak are fairly easy to access.

This doesn’t happen a lot, but it happens more in severe climates where harsh winters can cause a lot of shifting and expanding.

Shell Leaks

Leaks in the pool shell can happen in any type of pool. Vinyl liners can tear or separate at the seams, or they can leak around fittings, such as lights, drains, and returns.

Concrete pool shells can sometimes crack, especially around the pipes that come through the service. And fiberglass shells can do the same thing.

5 Warning Signs of a Swimming Pool Leak

There are a few obvious and sometimes, not-so-obvious, signs to look for that might indicate a pool leak.

1. Water Loss

Of course, water loss is the biggest sign of a pool leak, but keep in mind you will lose a little water due to evaporation, especially on hot days. But if you notice your water getting much lower than normal or in addition, there are a few other signs you should look out for.

2. Cracking or Shifting Tiles

The ground around the pool will naturally shift, but if you start to see a lot of cracks or big gaps, it could be a sign that there’s a leak somewhere. This would be caused by excess water in the surrounding soil.

3. Higher Water Bills

If your water is seeping out enough to make your water bill shoot up, you’ve probably already noticed lower water levels in the pool. However, many people have automatic fill devices that keep those levels where they’re supposed to be.

In these cases, you might not realize it until you get that sky-high bill and wonder what’s going on.

4. Algae Growth

Same thing here. If you have an auto-fill device, all that new water could be messing with your pool chemistry  and diluting the sanitizer. When this happens, algae will usually start to bloom more frequently than you’re used to.

5. Puddles in the Yard

Obviously, these can also be explained by a recent rain or watering your lawn. But if you start to notice wet spots that don’t seem to dry up, you could have some underground plumbing leaks.

Pool Leak Detection: 2 Testing Methods

If you do suspect a leak, there are a couple of methods you can use to test for them. But for leaks that may be in the underground plumbing, you’ll probably need to call in a professional to do a pressure test.

1. Bucket Method

The bucket method is probably the easiest and most popular method because it can help you rule out evaporation as an explanation for your water loss.

For this method, you’ll put a 5-gallon bucket of water beside the pool and mark the water line in both the pool and the bucket and turn off the pool pump. After 24 hours, if the pool loses more water than the bucket, you probably have a leak.

But if they both seem to have about the same amount of loss, it’s likely just normal loss due to evaporation.

OR you can place the bucket on the second or third step in your pool and fill it with water, making it even to your pool’s water level. Then, after 24 hours, if the pool water level is lower than the bucket level, you can assume you have a leak.

2. Ink Method

The ink method involves using a leak finder dye or dark food coloring. It’s only effective if you have an idea of the general area the leak might be coming from.

To perform it, you might need some goggles so you can see clearly underwater while you work.

All you do is squirt the dye in the water very close to the wall where the suspected leak is. If you are in the vicinity, the dye will start to move toward it and seep through it.

Just make sure you are as still as possible while using this test so you don’t disturb the dye with your own movements.

How To Repair Your Swimming Pool Leak

How you fix your leak will, of course, depend on where it is. If it’s an underground plumbing leak, you’ll most likely have to call in a professional unless you’re one yourself. But most other leaks can usually be fixed with no problem.

Skimmer Leaks

For skimmer leaks, underwater pool putty is your best option. First, shut off the pool pump to keep the water as still as possible.

Next, remove the skimmer cover. Now, just apply the epoxy putty per the manufacturer’s instructions to the leaky area.

Usually, you’ll just apply it with your fingertips and smooth it into the entire crack.

Finally, replace the skimmer cover and tighten all the screws well.

Liner Leaks

It’s also a good idea to call a professional to fix a vinyl liner leak so that you don’t accidentally mess it up. But if your leak is pretty visible and you know exactly where it is, you can fix it yourself if you’re careful.

Simply buy a vinyl patch kit made for pools and get to work. Each kit’s instructions might vary a little, so just be sure to follow those exactly.

Tile Leaks

Concrete pools tend to develop leaks where the bond beam starts cracking behind the tile. These can be fixed using silicone caulk or some type of tile and stone patch.

Shell Leaks

Most concrete cracks don’t leak unless they’re pretty deep. But if you have detected that’s where water is getting out, you can use pool putty, silicone caulk, or some type of concrete or stone patch material to seal it up.

Pool Leak Detection FAQs

How does pool leak detection work?

Finding a pool leak yourself is sometimes pretty hard to do, especially if it’s a tiny little liner tear or puncture.

But we listed 2 methods to try. These both include different steps to find the most common types of leaks.

The bucket test works by allowing you to see if your pool is losing water due to evaporation or an actual leak. And the ink test shows you where water is seeping out by watching the flow of the dye.

Professional leak detectors use items like electrical probes to track the sources of “least resistant connections.” These send them audible frequencies letting them know where the voltage is weak.

They also might use a pressure method where they can tell where the plumbing is losing water pressure.

How much does it cost to find a pool leak?

The cost for pool leak detection varies, depending on what method you’re using or if you decide to hire someone.

A DIY kit can cost anywhere from a few dollars to $30 or $40. Hiring a professional can cost quite a bit more. FIXr lists the national average for this cost at $900 but shows it can run up into the thousands for things like cracked beams or complete tile replacement.

How can I tell if my pool is leaking from dye?

Using dye to test for a pool leak is usually called the “Ink Method.” The reason this works is that the water surrounding the leaking area is trying to escape through the opening.

When you squirt dye close to it, you can see it trailing off with the escaping water.


Pool leaks are not always super easy to find, but with these methods and a little patience, it is possible. Just know that big repairs, especially in the plumbing, are much better off being handled by a professional.

It may cost a little more, but you won’t risk tearing up your expensive equipment and causing the need for bigger repairs than you started with.

Take it from someone who’s caused a few minor disasters in the name of DIY!