Even a tiny pool leak can cause more trouble than you might expect. Water disappears faster than it should, chemicals get out of balance, and equipment can take a hit. Some leaks start small and go unnoticed until your water bill jumps or your pool always seems low.
Knowing how to detect a pool leak early and taking the right steps can save time, money, and frustration. Understanding where leaks commonly appear and what you can fix yourself makes keeping your pool in top shape much easier.
Signs your pool might be leaking
Before doing any tests, watch for a few tell-tale signs. Pools normally lose about 3–7 mm per day just to evaporation, so if your water level is dropping faster than this, it’s likely a leak. You might notice wet or sunken areas around the pool, spiking water bills, or the need to add chemicals more often. Noisy pumps, gurgling return lines, or visible cracks, missing tiles, or small liner tears are also warning signs that water is escaping.
If you notice any of these signs, it’s time to start finding the leak in your pool before the problem gets worse.
How to find a leak in a pool
- Check it isn’t just evaporation (bucket test)
Start by ruling out normal water loss from evaporation. You’ll need a 15–20 litre bucket, a marker, and some tape. Place the bucket on the second step of your pool, fill it so the water inside matches the pool’s level, and mark both waterlines. Turn off any auto-fill systems and leave the bucket for 24 hours. If the pool water drops more than the bucket, it’s a strong sign that you have a leak. - Test under pressure
Next, refill both the bucket and the pool to the marks, then run the pump continuously for 24 hours. If water loss increases while the pump is on, the leak is likely in pressurised plumbing or equipment, such as return lines, pump seals, or filter fittings. Modern, energy-efficient pool pumps are also less prone to seal wear, so upgrading your pump can sometimes reduce long-term leak risks. If the water loss stays about the same, it suggests the problem is structural, in the liner, or in a non-pressurised fitting. - Narrow down the leak level
Let the water settle and observe where it stops dropping—high, mid, or low. If the level stops above the skimmer, the leak may be at the skimmer wall or a return fitting. If it falls below the skimmer mouth and then plateaus, this often indicates a skimmer or return leak. This “level plateau” behaviour is a classic clue when locating pool leaks. - Do a visual sweep
With the equipment turned off, walk around the pool and inspect the surrounding area. Look for wet soil, sunken patches in the lawn, loose tiles, or cracks in the pool shell. Check the pump, filter, and pipe fittings for any dripping water, and tighten any loose unions or fittings. Careful observation at this stage can reveal obvious sources of leaks before you move on to more detailed testing. - Use the dye test
Finally, the dye test can confirm suspicions. Turn off all equipment and let the water calm, then squirt a small amount of dark food colouring near areas you suspect, such as skimmers, lights, or liner seams. Watch to see if the dye is drawn into a leak. Underwater areas are easier to check with goggles or a snorkel. Mark any identified problem spots with tape or pencil for repair. This simple pool leak test is particularly useful for liner tears, tile cracks, or leaking light fittings.For extra accuracy, a swimming pool leak detection kit can also help pinpoint small or hidden leaks.
Common pool leak trouble spots
Once you’ve pinpointed the general area of a leak, it helps to know the areas where swimming pool leaks most commonly occur: Understanding these typical trouble areas makes it easier to identify the source and decide whether a DIY fix is possible or professional help is needed.
Skimmers: Check where the skimmer meets the pool wall. Small gaps can be sealed with waterproof pool putty or silicone. If the water drops to the bottom of the skimmer and then slows, it’s often a skimmer-throat leak.
Vinyl liners: These typically last 6–12 years. Small tears above water can be patched with dry kits, underwater holes with wet kits. Large rips or ragged seams usually need a replacement liner.
Pool lights: Leaks here usually come from the conduit or fixture seals. Electrical risk means calling a professional is safest.
Returns and fittings (plumbing): Replace worn O-rings, gaskets, and tighten unions. Leaks under pressure may need disassembly to reseal or replace parts.
Structural cracks: Fine plaster or concrete cracks can be patched with pool-grade repair compounds. Large cracks or bulging walls require professional attention.
Equipment and fittings: Leaks can also develop around pool heaters and heat pumps, particularly if seals age or housing cracks. Pay close attention to your heater and pump connections, as even small drips here can go unnoticed for a long time. Choosing a well-installed, energy-efficient swimming pool heat pump keeps the water comfortable year-round while also reducing the risk of leaks linked to worn or stressed equipment.
DIY fixes vs calling a professional
Many minor leaks, such as small liner tears, skimmer gaskets, or fittings, can usually be repaired at home. After making any fix, it is important to re-test using the bucket or dye method to ensure the leak has truly been resolved.
It is wise to call a professional if the water loss is rapid, several centimetres per day, or if the leak involves plumbing, electrical components, or major structural elements. You should also seek expert help if you are unsure how to safely carry out the repair. Professionals have specialised tools, such as pressure testers and acoustic detectors, that can quickly locate hidden leaks. Ignoring a serious leak can result in soil erosion under your pool or deck, leading to costly and potentially dangerous damage.
How to prevent swimming pool leaks
Regular inspection goes a long way in keeping your pool watertight. Periodically check hoses, pipes, seals, and O-rings, and maintain steady water levels to avoid putting stress on the liner or plumbing. Using a pool cover when the pool is idle can reduce evaporation by up to 90 percent and also protect the liner from debris. Winterising your pool helps prevent freeze damage, and careful landscaping can prevent problems from tree roots or shifting soil putting pressure on pool walls.
Scheduling annual professional inspections can save money in the long term by checking plumbing, the pool shell, and equipment seals, ensuring everything remains in good condition.
