How to Find a Leak in Your Swimming Pool

loose deck boards around a pool

It’s always good to look at the glass half full. But in the case of swimming pools, you should look at it half empty and find the problem. If your pool has lost a significant amount of water in a short period of time, it’s a clear sign of a leak. Wondering how to find a leak in your swimming pool? You can look for evidence around your pool, perform a dye test, or compare water levels with a plastic bucket. 

Leaks are a common problem with swimming pools and should be quickly located to stop them from causing bigger problems. In addition to the materials needed, we have listed all the steps required to test for leaks in and around your swimming pool. 

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But First, Follow Safety Measures

No matter the home improvement or maintenance task, you should always make safety the top priority. When it comes to detecting a leak underwater, drowning is arguably the most dangerous hazard. If you can’t hold your breath long enough, avoid dives in the deep end of your pool. Here are more safety measures to consider:

  • To prevent shock, do not touch wet electrical wires.
  • Work carefully around your pool’s edges to avoid falling in.
  • Keep an eye on your kids and pets while you’re busy working. Keep the pool gate closed to avoid them slipping in, especially when you’re checking for leaks underwater.
  • Avoid swimming pool repairs if your area’s expecting an electrical storm.
  • Use safety goggles to protect your eyes from chemicals (dye test).

Tools Needed for Pool Leak Detection

Here are the tools you need to purchase to help you detect leaks in your swimming pool:

  • Goggles
  • Plastic 5-gallon bucket
  • Permanent marker
  • Syringe
  • Swimming pool leak detection dye
  • Underwater patch repair kit
  • Duct tape (or waterproof tape)

How to Find a Leak in Your Swimming Pool

A pool pump and filtration system
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Step 1: Look for Evidence Around Your Pool

If it sounds like a simple task, that’s because it is. This process helps you determine which area of your pool to focus on.

  • Take a walk between the pool and equipment pad to spot any changes in the ground. 
  • Keep an eye out for puddles of water in the grass, cracked pool tiles, and cracked concrete (including the pool deck).
  • Look for cracks in the vinyl liner.
  • Check the pool skimmer separating from your concrete pool.

What you’re looking for may depend on the type of pool you have installed, but these are generally the main issues you should keep an eye out for. 

However, there’s one external factor that may point to a leak, and that is your water bill. If you notice a sudden increase in the bill, then your pool may be suffering from a leak. This mainly applies to systems that automatically level the pool water. 

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Step 2: Confirm Pool Leak With the Bucket Test

This is an old-school, DIY-friendly method to help you verify a leaking swimming pool. Essentially, the bucket test helps you know if you’re losing pool water due to a leak or evaporation. The materials you’ll need are a 5-gallon plastic bucket and a waterproof marker (or duct tape). 

Remember to turn off the pool pump before commencing this test. You’ll also need to run this test on a day with absolutely no rainfall. Here are the steps of the bucket test;

  • Switch off pump: Turn off the pool pump and any other auto-refill device to keep the water still. 
  • Fill and place the bucket: Start by filling the 5-gallon bucket with water to match the pool’s water level. Set the bucket on one of the steps leading into the pool (ideally the second). It should be about half underwater. 
  • Mark the water level: Use the waterproof marker or duct tape to mark the water level inside the bucket, then mark the pool water level on the outside. Leave it alone for at least 24 hours.
  • Compare water levels: After waiting 24 hours, compare the pool water level to the level of water in the bucket. If both levels have gone down but remain even, then it’s just a case of water evaporation. If the pool water level is lower than the bucket’s water, then you’re dealing with a leak. 

The bucket test is a simple method to verify whether the water loss is due to evaporation or a leak. The next step would be to determine the source of the leak and fix the issue, but we’ll get to that later. 

Step 3: Check on the Equipment Pad

This step includes checking for a part of the pool equipment that has failed or a connection seal that has broken. Each of these cases will allow water to leak into the pad. Corrosion on parts of the equipment pad is another clear sign of a water leak. 

Damaged valves and pool heaters may also result in leaks and the loss of water from your pool system. If you own a concrete pool, check on the skimmer, which is a common location for pool leaks. 

Step 4: Check Pool Pump and Filtration System

When performing tests to check for leaks, the pool water needs to be still. For this reason, you must turn off the pool pump and filtration system. 

However, the pump and filtration system themselves can be suffering from leaks. For a filter test, you can switch it off and check for trickling water. A minor leak can be the result of loose fittings.

Running an additional bucket test with the circulation switched on is another way to spot a leak. If the water levels are different when the pump is on (but the same when it’s off), then the leak is coming from the plumbing or filtration system. 

In severe cases of leaks, you should hire a professional to prevent further damage and avoid getting shocked by wet electrical wiring. 

Step 5: Leak Detection: Dye Test   

The dye test is more precise than the bucket test, as it helps you find the exact location of the leak (that is if the leak is not in the plumbing or filtration system). For this test, you’ll need a leak-detection dye and waterproof tape to mark the leaky spots. Food coloring is another alternative to the leak detection dye. 

What are the steps to complete a successful dye test? 

  • Check the ground and walls around the pool: You should look around for any wet spots around the swimming pool. If the ground is wet where it shouldn’t be, then the pool leak is near that area. Try to pinpoint the exact location to know where to apply the pool dye. For an above-ground pool, you can check the pool sides for any wet spots.
  • Switch off pool pump: Similar to the bucket test, turn off the pool pump and pool circulation equipment. You’ll need the pool water to be as still as possible before using the dye or food coloring. 
  • Apply the leak detection dye: Go to the edge of the pool and near the location where you suspect the leak to be. Be sure not to touch the water and keep it still. Squeeze a small amount of the dye near the pool wall, skimmer, lights, or other fittings in your pool.
  • Leak confirmation: If the worst has happened, the dye will move towards the exact location of the pool leak. 
  • Mark the spot: It’s unfortunate that you have a pool leak, but you’ll need to mark the spot with waterproof tape to remember where temporary patching is required. 

Note: If neither of these testing methods helps you determine the location of the issue, then you may have a leak in the underground pool plumbing system. You’ll need to hire professionals to fix such a case. Pool professionals will use ultrasonic equipment to locate the leak. 

Signs of a Leaking Pool

Peeling swimming pool foil
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We now know the immediate actions to take if we suspect a pool leak. Apart from wet spots near the pool or water level drops, what other signs can help you identify a possible leak? 

  • Cracking tiles: You notice cracks in the pool’s surrounding tiles. The unstable ground is due to excess water that results from water seeping through. 
  • Algae growth: Algae may grow in your pool for several reasons, but a pool leak is certainly one of them. It is a general sign of compromised water quality. 
  • Water chemistry: Another sign of a leak is when your pool water chemistry levels fluctuate. 
  • Pool plumbing: If you notice wet terrain surrounding the pool plumbing, then you should determine the location of the leak and get it fixed. 

Common Locations for Pool Leaks

We may have covered the possible locations of pool leaks throughout the article, but it’s good to have a specific section with a clear list to help you remember! 

  • Skimmer: This mostly applies to owners of concrete swimming pools. If so, you should check for small holes, cracks, and weak spots. 
  • Return lines: These are vulnerable to leaks because they’re thin and made of similar material as skimmers. 
  • Pool lights: Such fittings that are installed into the pool wall are susceptible to damage or separation from the pool surface, potentially causing leaks. 
  • Bottom of the pool: The bottom floor or surface of the pool can be weak and an easy target for leaks. 

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Causes of Pool Leaks

pool construction
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No matter the type of swimming pool you have installed, leaks are a common issue that cannot always be avoided. It’s an unfortunate fact about pools, no matter how frequently you maintain the system. 

The three leading causes of pool leakage are fitting faults, structural flaws, and underground plumbing issues. 

  • Fitting faults: The fittings are what are installed underneath your pool shell such as jets, skimmers, and lights. They typically have plasters around them, making these areas of your pool vulnerable to leaks. 
  • Structural flaws: These may result in the pool wall itself. For example, a structural flaw in a concrete pool means a crack in the shell. Vinyl pools are just as susceptible to leaks, especially when the liner suffers from wear and tear. Ground movement, shifting soil, and pressure from groundwater may also cause pool leaks. 
  • Plumbing issues: A swimming pool’s plumbing system can be fragile, so it must be properly installed by expert technicians. Leaks in the plumbing system may result from ground movement near a pipe or possibly corrosion. 

Here are some less common causes of pool leaks that should also be considered:

  • Accidental hits during outdoor construction work
  • Rapid change in temperature
  • Imbalance in pool water chemicals
  • Improper pool winterization

Pool Leak Repairs: DIY or Hire Pool Pros? 

Generally, pool patches such as vinyl pool patch kits are temporary fixes. They can work for about a year but will reoccur once the patch wears off or deteriorates. 

We recommend hiring pool repair professionals to fix underground plumbing leaks, severe pool lining damage, and equipment pad issues. Pool experts can also perform pressure tests to determine issues with pump and filtration systems. 

There are some DIY-friendly repairs that do not require the trained hands of pool experts. You can fix a leak in pool fittings using silicone to cover the cracks or holes. Pool lights are such fittings that you can repair yourself. 

FAQ About Swimming Pool Leaks

Is there an equation to calculate water loss during the bucket test? 

Yes, there is! Here is an equation to help you determine how bad the pool leak is: 

Pool length (feet) x pool width (feet) x 0.625 x water loss (inches/24 hours) = total gallons of water lost

Do you ever need to drain the pool to repair leaks? 

In short, no. You should not drain your pool to test for or repair leaks. Even if a certain issue requires pool drainage to fix, it should be done by professionals. If you drain the pool yourself, it may cause further damage to your system. 

How much does pool maintenance cost on average? 

The annual cost of professional pool maintenance ranges from $2,000 to $4,035

The average cost of repairing a damaged pool is approximately $518, depending on the severity of the issue and pool type. 

Patches Are Temporary; Pro Repairs Last

You can patch up your pool to stop the leak, but it’s only a short-term solution. Weak spots and areas susceptible to leaks will find ways to come back and haunt you. Repair kits are useful to control leaks and prevent bigger problems, but you’ll need to hire the services of a pool company to effectively fix the issue. 

Severe cases like underground plumbing leaks require professional attention. Cracks in concrete pools are not easy for pool owners to fix. You can also prevent electrocution by avoiding wet electrical wires. 

Ready to fix your pool issue? Pool Gnome connects you with local pool repair pros who can get the job done at an affordable price. With just a few clicks, you’ll get quotes in minutes.

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Jeffery Keusseyan

Jeffery Keusseyan is a writer with a knack for research and handiperson skills. He enjoys writing about home improvement projects and efficient ways to maintain your home exterior.