A swimming pool is a valuable investment that provides years of enjoyment, but when leaks occur, they can quickly lead to high water bills, structural damage, and a frustrating maintenance cycle. Understanding the most likely cause of a pool leak helps homeowners detect issues early, save resources, and maintain a safe, beautiful pool environment.
This comprehensive guide explores the primary reasons pools leak, how to identify them, and why professional leak detection services are crucial. Whether you’re in Toronto, Durham Region, York Region, Simcoe County, Peel Region, or Muskoka, the information here is tailored to help you protect your pool and your property.
Understanding Pool Leak Basics
To appreciate the most likely cause of a pool leak, it helps to know how pool systems work. A typical pool includes components such as the pool shell, plumbing system, filtration unit, skimmer, and return jets. Leaks can form in any of these areas, but some are far more common than others.
Pool leaks are not always visible. In fact, the average pool loses 2 to 4 inches of water per week due to evaporation alone. However, if you’re refilling your pool more than once a week, suspect something more than evaporation.
What is the Most Likely Cause of a Pool Leak?
The most likely cause of a pool leak is a plumbing issue beneath the pool deck or around the pump and filter system. These hidden leaks often occur in the underground pipes that carry water to and from the pool. High water pressure, ground movement, aging pipes, or improper installation can all contribute.
In our field experience serving the Greater Toronto Area, we’ve found that over 60 percent of pool leaks are traced back to underground plumbing faults. These leaks can waste hundreds of gallons per day without showing any surface signs.
Let’s dive into the most common causes in detail.
1. Underground Plumbing Leaks
Underground plumbing leaks are the most likely cause of a pool leak. These often go unnoticed until homeowners see a sudden spike in water bills or discover wet spots around the pool area.
Key Signs:
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Constant need to refill the pool
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Soft or soggy spots near the pool deck
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Air bubbles in return jets
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Low water pressure in the filtration system
PVC pipes used in pool plumbing are durable, but soil shifting during seasonal changes in Ontario or high freeze-thaw cycles in areas like Muskoka and Simcoe County can crack them. In most cases, pressure testing and electronic leak detection are required to pinpoint the exact location.
2. Pool Skimmer Cracks
Another highly likely cause of a pool leak is a crack in the pool skimmer. The skimmer pulls in water to filter debris, and it’s typically made of plastic or concrete. If the skimmer separates from the pool wall or develops a hairline crack, water escapes into the surrounding soil.
Statistics show that skimmer leaks account for approximately 25 percent of pool leaks in residential pools in areas like Ajax, Pickering, and Whitby.
To detect a skimmer leak, turn off your pump and observe the water level. If it stabilizes right at the skimmer, a crack is highly probable.
3. Structural Cracks in Pool Shell
A structural crack in the pool shell is another potential culprit. These can occur in concrete or gunite pools due to ground movement, improper installation, or age-related deterioration.
While less common than plumbing leaks, structural damage causes roughly 10 percent of pool leaks in older pools across the GTA and Peel Region.
Warning Signs:
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Visible cracks along the pool floor or walls
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Consistent water loss even when the system is off
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Debris or algae consistently returning to the same spot
To confirm, a dye test is often performed around the suspected area. If the dye pulls into the crack, it indicates an active leak.
4. Loose or Damaged Pool Lights
Pool lights may not be the first thing you suspect, but they can be a surprising cause of pool leaks. Water can seep in through the light niche or the conduit that carries wires from the light to the junction box. Improper sealing or aged rubber gaskets often cause this issue.
About 5 percent of leaks we detect at Showtime Pools come from pool lighting systems, especially in vinyl liner pools. These leaks are generally slow but continuous, leading to gradual water loss over time.
5. Faulty Fittings and Returns
Any component that connects into the pool shell — including return jets, main drains, and vacuum lines — can leak if not properly sealed or if aging causes the gaskets to deteriorate.
As water constantly flows in and out of these fittings, even a small misalignment can result in a leak. Loose fittings are especially common after winter seasons in Canada when freezing temperatures cause expansion and contraction of materials.
If your pool leaks only while the pump is on, faulty return fittings are a likely cause.
Pool Leak Detection is a Specialized Task
Pinpointing the most likely cause of a pool leak is not a DIY job. At Showtime Pools, our team uses advanced technology such as ultrasonic listening devices, pressure testing systems, and infrared thermography to detect leaks without damaging your property.
In fact, we’ve helped hundreds of homeowners across Oshawa, Uxbridge, and Vaughan detect and repair pool leaks within 24 to 72 hours from the initial inspection.
Our process includes:
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Pressure testing of underground lines
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Dye testing for surface-level leaks
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Electronic skimmer inspections
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Subsurface acoustic testing for buried leaks
Once the leak is found, we provide clear recommendations and high-quality repairs to ensure long-term performance.
Why You Should Act Quickly
A leak that loses even half an inch of water per day can result in over 10,000 liters of water lost per month. That’s not just wasteful — it’s costly and potentially damaging to nearby structures.
Left unaddressed, a pool leak can lead to:
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Soil erosion beneath the pool
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Cracked foundation or lifted deck
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Increased chemical use
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Poor filtration performance
Timely action preserves your investment and ensures your pool remains safe, clean, and efficient throughout the season.
Homeowner Tips to Detect Early Signs
Here are a few practical steps pool owners in the Toronto region can take to catch leaks early:
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Perform the bucket test: Fill a bucket with water and place it on the pool step. Mark both water levels. If the pool water drops more than the bucket water in 24 hours, you likely have a leak.
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Inspect around fittings: Look for water stains or algae near jets and light niches.
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Monitor your water meter: If it’s running while the pool system is off, a hidden leak may be to blame.
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Log your refill frequency: If you’re adding water more than once a week, have a professional inspection done.
Trust Showtime Pools for Expert Detection
At Showtime Pools, we specialize in Pool Leak Detection and Repair, serving Toronto, GTA, York Region, Durham Region, Peel, Simcoe County, and Muskoka. We combine precision, speed, and customer care to ensure your pool issues are solved with minimal disruption.
Our technicians bring over a decade of field experience and use non-invasive detection techniques to locate leaks accurately and repair them efficiently.
If you suspect a leak in your pool, don’t wait. Catching the issue early can save you time, money, and frustration.
Summary
What is the most likely cause of a pool leak? In most cases, it’s underground plumbing or a cracked skimmer. However, other culprits include faulty fittings, structural damage, or pool lighting issues. Identifying the cause requires expertise, the right tools, and a clear process — all of which we provide at Showtime Pools.
Whether you’re in Toronto, Ajax, Pickering, or Muskoka, our goal is to help you maintain a safe, efficient, and leak-free pool all season long.
For inspections or service inquiries, contact Showtime Pools:
Phone: (289) 264-1250
Email: info@poolleakdetection.com
Website: www.PoolLeakDetection.com