How To Spot A Leak In A Pool


Pool leaks are one of the worst nightmares a pool owner can experience. They can happen under the radar and can be pretty difficult to detect. Luckily, there are a ton of ways to spot a leak in a swimming pool. 

A Must-Read: Best Pool Accessories

You may have noticed that your pool’s water level has significantly lowered. The good news is, it may be just due to evaporation. Worst case scenario? A leak. 

Is It A Leak Or Just Evaporation? 

Depending on pool size and weather, you normally lose up to 1 ½ inches to 4 inches per week just from evaporation. That’s about ¼ – ½ inches lost every day. 

There are also times where your pool may evaporate faster than normal. Here’s why: 

  • Sun exposure: The main cause of evaporation is the sun and the heat it delivers. 
  • Temperature: Different areas have different temperatures. The hotter the area you live in, the faster evaporation there is for your pool. 
  • Humidity: Pools evaporate much faster in areas where humidity is low due to dry air absorbing vapor. 

Now that we know how evaporation affects swimming pools, when can we rule out the possibility of one?

Bucket Test

The thing is, you can never be too sure if it’s really a leak unless you incorporate a little experiment. 

Doing the bucket test is the most popular method for confirming your suspicions of leaks. It’s a simple and easy experiment that uses a bucket of water as a point of reference for ever-changing water levels. 

To do the experiment, you’ll need a few tools: 

  • Bucket
  • Marker (pen or duct tape will do)
  • Measuring device
  1. Place the bucket on the first step of the pool. 
  2. Using pool water, fill the bucket until the level is slightly higher than the pool water level outside of the bucket. 
  3. Mark both levels with duct tape or marker. 
  4. After 24 hours, measure the results on both water levels then compare using your measuring device. 

The whole point of using a water-filled bucket is to simulate the environment your pool water is in. You can expect either of these two results: 

  • If your pool water level loses more than the bucket water level, you have a leak
  • If your bucket level and pool water level decreased roughly at the same rate, it’s just evaporation

You need to do this test under the following conditions: 

  • There has to be no rain within those 24 hours of testing
  • Do not use the pool within the duration of testing
  • Avoid covering the pool
  • Do the test at exactly 24 hours. Waiting for more than that may give you inaccurate results

Locating Your Leak 

Thanks to the bucket test, you now know that you’ve got yourself a leak. But the pool has such complicated anatomy, not to mention it covers a sizeable surface area. It’s such a tedious task to go at it inch by inch!

So, to make things easier, let’s go at it methodically with these processes: 

Bucket Test With The Pump ON

Remember the bucket test you did with the pump off? You can actually get more data from that by playing with the variables. This time, you turn the pump on.

Doing this will give you a better idea WHERE your leak may be. 

Below are the possible results from the pool pump on and off test: 

  • If you lose more water with the pump on, the problem may be with pressure-side plumbing
  • If you lose more water with the pump off, the problem may be with suction-side plumbing
  • If water loss is equal with both the water pump on and off, check the pool itself

Note that these are just rough estimates and may result may be false due to varying environmental conditions during the test. 

Either way, controlling your variables is a good start for tracking down a leak.

Inspect Your Pool Structure

Pool leaks can affect some structures nearby to it. For instance, a sinking or cracked pool deck may likely be a sign of a pool leak near the affected area. 

Other signs may include: 

  • Rust around the skimmer and return ports
  • Patched holes in your pool liner
  • Cracks in the pool floor
  • Broken pool fittings

Basically, keeping an eye out for any suspicious damage is one step to detect a pool leak. 

In the event you do find one, the necessary step to take next is the pool dye test.

Pool Dye Test 

The goal of the dye test is to track the movement of the dye pigment, so be sure your pool water is still. 

Executing this test in shaky water can be very hard. That’s why it’s best you switch off your pool’s circulation system and keep the water stagnant as much as possible. Even a gust of wind or your hand moving in the pool can be significantly disruptive to the test. 

With that in mind, here are the simple steps for the dye test: 

  1. Ready your dye. Any dark food coloring is best for easier detection. 
  2. Prepare your goggles. You will be submerging yourself to locate the leak properly.
  3. Keep the water still by turning off your pool’s circulation system.
  4. Release the dye in cracked areas or wherever you think the leak may stem from.
  5. If the dye gets sucked in the crack, you have a leak. 

Take note that while the dye test might sound simple on paper, it’s actually pretty hard to execute. Many beginners have high expectations with the dye test, assuming they’ll magically find the leak with ease thanks to the dye. 

But unless you have a big leak in the surface of your pool, there’s a high chance you’ll be having a hard time actually detecting the leak with just a dye. 

Nonetheless, the dye test is part of every pool owner’s arsenal because of the simple tools used. It’s definitely worth giving a shot. 

That said, check out this dye tester from Amazon for easier leak detection.

How To Spot A Leak In A Pool

Isolation System

When all else fails, it’s time to manually isolate the pool leak. 

Swimming pools can be divided into two main components: 

  • Pool structure
  • Pool plumbing system

You’ll need to separate these two in order to pinpoint where your leak may be coming from. Here are the steps: 

  1. Plug up all your pool ports with a winterizing plug. 
  2. Switch off the pool’s filtration system and plug up the skimmer and return ports. 
  3. Let the pool sit for 24 hours with all the ports plugged up to measure water loss. 
  4. Compare water loss from when the pool ports are all exposed and left open. 

Doing this test yields the following results: 

  • If the pool loses water while the pool ports are plugged, the leak may be located in the pool structure itself
  • If the pool loses water while the pool ports are open, the leak may be located somewhere in the plumbing system

Call In A Professional 

Some leaks can be really tricky to find, and that’s only natural. In this case, you may want to call in help from a professional. 

They will incorporate sophisticated processes to locate a leak such as: 

  • Pressurizing: For leaks located in pool plumbing, the experts will use compressed air to add pressure to the pipes. This method will isolate the leak by detecting where the air pressure falls along the pipe. 
  • Camera: Instead of compressed air, experts will use a camera installed with a sensitive microphone in order to detect a leak. 

Fixing A Pool Leak 

Leaks are more prominent in some areas. Here’s a rough guide on how to deal with them: 

  • Skimmer leaks – can be fixed with a pool putty
  • Light leaks – can be fixed with a two-part epoxy that dries hard plus a pool putty, silicone, or caulk
  • Liner leaks – can be fixed with a vinyl patch kit

Here is some pool putty you can get on the cheap.

How To Spot A Leak In A Pool

Different pools also require different leak-fixing methods. Is your pool fiberglass, concrete, or vinyl? 

If you have a vinyl pool liner, you don’t necessarily have to replace it. You can purchase a vinyl liner patch kit to solve your leak problems. The kit comes with a big sheet of vinyl. 

  1. Cut a circular portion slightly larger than the hole then apply glue on the back of it. 
  2. Locate the hole and place the cut liner atop the hole. 
  3. Apply pressure for two minutes. 

CAUTION: Never drain your vinyl pool completely. Vinyl liners are very fragile and are meant to be submerged in water at all times. Exposing it on air will dry up and wrinkle like a raising, causing tears and rips. 

A concrete pool, on the other hand, requires a relatively sophisticated procedure when it comes to fixing leaks. You’ll need to do a repair plaster to cover them. 

Wrap Up 

In most cases, evaporation can be easily mistaken for pool leaks. There’s no need to panic if you notice a suspicious amount of water vanishing. The most logical (and simplest) thing to do is DIY your way through it with a detection test! 

Should you wish to contact a professional service provider for taking care of your leaks, you can make it easier for them by giving them the results of your detection test.

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