Is Your Toronto Pool Losing More Water Than It Should?
Every inground pool loses some water through evaporation and splash-out. That is normal. But if you are topping up your pool every few days, noticing soggy patches on the lawn near the equipment pad, or hearing strange gurgling sounds from the skimmer, something else may be going on. A plumbing leak inside your pool’s underground pipe network can go undetected for months, quietly eroding soil, stressing your pool structure, and inflating your water bill the entire time.
Toronto’s freeze-thaw cycles are hard on buried PVC pipe. Each winter, frost pressure and ground movement stress joints and fittings that seemed solid the season before. Spring openings are when many homeowners first notice something is wrong. Knowing what to look for and how to do a basic self-test at home can help you catch a problem early and communicate it clearly to a professional when you call.
This guide covers the most reliable warning signs of a pool plumbing leak, how to run a simple bucket test, and the steps to take once you suspect there is an issue. For a broader look at keeping your pool in top shape throughout the year, see our inground pool maintenance guide for Toronto homeowners.
Start Here: The Bucket Test
Before assuming a plumbing problem, rule out normal evaporation with a bucket test. It takes 48 hours and no special equipment.
- Fill a standard 5-gallon bucket with pool water and set it on the first or second step of the pool so it sits at the same air temperature as the pool surface.
- Mark the water level inside the bucket with tape or a marker. Mark the pool water level at the skimmer or pool wall.
- Turn off the pump. Leave both marks undisturbed for 24 hours, then note how much each has dropped.
- Refill to the original marks. Run the pump for the next 24 hours, then check both levels again.
Reading the results: If the pool and bucket lose about the same amount in both rounds, you are dealing with normal evaporation. If the pool drops more than the bucket when the pump is off, the leak is likely in the shell, liner, or main drain area. If the pool drops significantly more when the pump is running, the leak is almost certainly in the pressurized plumbing system.
8 Signs Your Pool Has a Plumbing Leak
1. Water Loss Beyond Normal Evaporation
On a hot, sunny, windy Toronto summer day, an uncovered pool can lose up to half an inch of water to evaporation. Anything consistently beyond that is worth investigating. If you are adding more than an inch and a half to two inches of water per week during normal weather, run the bucket test before calling anyone.
2. Wet or Soggy Ground Near the Plumbing Lines
Underground leaks push water toward the surface. Walk the perimeter of your pool and pay close attention to the area between the pool shell and your equipment pad. Soft or mushy ground, unusually lush grass in a narrow strip, or water pooling near the pump or filter are all warning signs that water is escaping underground.
3. Air Bubbles in the Return Jets
When a suction-side pipe has a crack or a loose fitting, the pump pulls air into the system alongside water. That air gets expelled through the return jets and shows up as a steady stream of small bubbles. An occasional bubble is nothing to worry about. Persistent bubbling every time the pump runs is a sign the system is drawing air in from outside the closed plumbing loop.
4. Gurgling or Sucking Sounds at the Skimmer
A healthy skimmer pulls water and debris in smoothly and quietly. If you hear loud gurgling or a sucking sound at the skimmer basket, the pump may be starved for water because air is entering the suction line. This commonly points to a leak in the pipe running between the skimmer and the pump intake.
5. Reduced Flow or Low Pump Pressure
A pump that struggles to prime, weak flow at the returns, or a filter pressure gauge reading lower than usual can all point to a suction-side leak. The pump is designed to move a set volume of water. When some of that water escapes through a crack before it reaches the pump, output pressure and flow both drop.
6. Cracks or Settling in the Pool Deck
A slow underground leak saturates the soil and changes its load-bearing characteristics. Over time, this creates voids and uneven settlement beneath your pool deck. New cracks running through concrete, lifting interlock pavers, or sections of deck that flex or feel hollow underfoot can all be symptoms of a plumbing leak rather than ordinary ground movement.
7. Dirt or Sand Entering Through the Returns
Fine particles of dirt or sand blowing into the pool through the return inlets indicate that outside material is being pulled into the suction line through a crack. Underground pipe cracks often have soil pressing against the outside of the pipe. When soil pressure is greater than internal water pressure, debris gets drawn in through the breach.
8. Higher Water Bills Without a Clear Cause
A sustained plumbing leak means constant top-up. If your water bill has climbed through pool season without explanation, and you are adding water to the pool more frequently than in past summers, tracking both data points together is a useful early diagnostic step.
| Symptom | Most Likely Location | Urgency |
|---|---|---|
| Air bubbles in return jets | Suction-side pipe or fitting | High |
| Wet ground near equipment pad | Pressure-side pipe near pump or filter | High |
| Gurgling at the skimmer | Skimmer-to-pump suction line | Medium-High |
| Dirt entering through return jets | Underground suction line crack | High |
| Deck cracking or settling | Deep underground line | Medium |
| Water loss greater when pump is on | Pressure-side plumbing | High |
| Water loss greater when pump is off | Shell, liner, or main drain area | Medium |
Suction Side vs. Pressure Side: Why the Difference Matters
Pool plumbing is split into two sides by the pump. Understanding the distinction helps you interpret what you are observing and communicate it clearly to a contractor.
Suction-side pipes run from the skimmers and main drain to the pump intake. When these lines leak, the pump draws air in instead of a full column of water. The main symptoms are air-related: bubbles at the returns, gurgling at the skimmer, and a pump that struggles to maintain prime.
Pressure-side pipes run from the pump outlet through the filter, heater (if installed), and back to the pool through the return inlets. When these lines leak, water is actively forced out of the system under pump pressure. You will typically see wet ground, saturated soil, or depressions forming near the pipe runs beneath your deck or lawn.
Pressure-side leaks tend to waste more water faster because the pump is pushing water through the breach. Suction-side leaks can sometimes cause less immediate water loss but will damage pump seals and motor bearings over time if air ingestion is not addressed.
What to Do When You Suspect a Plumbing Leak
- Run the bucket test first to confirm the loss is in the plumbing system rather than the liner, shell, or through normal evaporation.
- Document what you are seeing. Photograph wet areas, log the water level daily, and note whether loss is worse with the pump on or off. This information is genuinely useful for the technician arriving to diagnose the issue.
- Shut off the pump if you are seeing significant water loss or continuous air bubbling, to avoid running the pump dry or accelerating wear on the motor seals.
- Contact a pool professional for formal leak detection. Locating underground leaks typically requires pressure-testing each plumbing line individually, and sometimes electronic listening equipment or dye testing at fittings and around the main drain.
- Understand the repair scope before anything is dug up. Underground line repairs usually require excavating access to the damaged section. That may mean cutting into your pool deck or removing planted areas near the equipment pad. Get a clear written scope before any work begins.
If your pool has been showing structural wear alongside the plumbing issue, it may make sense to combine leak repair with a broader pool restoration project. Our guide on pool restoration vs. replacement in Toronto walks through how to evaluate your options before committing to a scope of work.
Understanding how underground plumbing is installed during a pool build can also help you anticipate which sections are most vulnerable. Our step-by-step guide to pool construction in Toronto covers the full build process, including how the plumbing runs are laid out and what materials are used.
Frequently Asked Questions
How much water loss is normal for a Toronto pool?
Most inground pools lose between a quarter-inch and half an inch of water per day through evaporation, depending on temperature, wind, sunlight, and whether the pool is covered overnight. Consistent loss beyond that range warrants a bucket test to separate normal evaporation from a leak.
Can a pool plumbing leak damage my home’s foundation?
In serious cases, yes. A sustained underground leak saturates the surrounding soil, which can lead to erosion, voids, and uneven settlement of pool decking. If the leaking line runs close to your home’s foundation, prolonged saturation creates real risk for foundation movement. Plumbing leaks should be addressed promptly rather than monitored over multiple seasons.
How do leak detection professionals locate underground pool pipe leaks?
The standard method is pressure testing each plumbing line individually by plugging one end and pressurizing with air or water. A line that cannot hold pressure has a breach somewhere along its run. Technicians also use electronic listening devices to pinpoint the crack’s location underground, and dye testing at fittings and the main drain to identify slower seeping leaks.
Does fixing a pool plumbing leak require draining the pool?
Not always. Some leaks at above-ground fittings or at the equipment pad can be repaired without draining. Underground line repairs typically require excavating to the damaged pipe section, but whether a full drain is needed depends on the location and depth of the breach. Your contractor will specify the scope based on the diagnosis.
Are Toronto pools more prone to plumbing leaks than pools in warmer climates?
Yes. Ontario’s freeze-thaw cycles put significant annual stress on underground PVC joints. Even properly winterized pools experience ground movement as frost penetrates and retreats each season. Glued joints that were watertight at installation can develop micro-cracks over 10 to 15 years that gradually widen. Annual pressure checks at spring opening are the best way to catch developing issues before they become major excavation jobs.
Think You Have a Leak? Let’s Take a Look.
If you are seeing any of the signs described above, the sooner you get a professional assessment, the better. At Destination Pools and Landscaping, we work with Toronto homeowners to diagnose pool problems, carry out pool restoration and repair, and keep backyards functioning and looking great through every season.
Whether it is a plumbing repair, a full restoration, or help planning a complete outdoor living upgrade, our team is ready to help you figure out the right next step.
Contact Destination Pools and Landscaping for a consultation.
