A swimming pool losing water is one of the most frustrating issues an Australian homeowner can face. You top it up, and a day later the level has dropped again. Before you blame the summer heat, it is worth knowing that evaporation alone rarely accounts for significant water loss. If your pool is dropping more than 5 to 6 mm per day, there is a good chance you have an actual leak on your hands. Finding it early can save you hundreds of dollars in water bills and prevent serious structural damage to your pool and surrounding property.

Is It Evaporation or a Leak?

Wind, direct sunlight, humidity, and water temperature all affect evaporation rates. On hot Melbourne days, losses of 3 to 5 mm are completely normal. Anything beyond that warrants a closer look.

Common Sources of Pool Leaks

Pool leaks can come from several places, and not all of them are obvious. Here are the most common:

Shell cracks and surface damage — Over time, concrete and fibreglass pools can develop hairline cracks, particularly around fittings, steps, and the waterline. These are often invisible to the naked eye but can allow a surprising amount of water to escape daily.

Fittings and returns — The areas around pool lights, skimmer boxes, return jets, and main drains are common weak points. The sealants around these fittings degrade with age and UV exposure.

Plumbing leaks — Underground pipes connecting your pump, filter, and pool can develop cracks or joint failures. These are harder to detect without pressure testing the plumbing system.

Pump and filter equipment — Loose connections, worn O-rings, and cracked filter housings can all cause water loss at the equipment pad.

How to Locate the Leak

Once you have confirmed a leak exists, the next step is narrowing down its location. Start by checking the equipment area — look for damp ground, mineral deposits, or visible drips around your pump, filter, and valves.

For shell leaks, a dye test is a practical DIY method. Turn off the pump and let the water settle. Using a syringe or squeeze bottle, release a small amount of pool dye near suspected crack areas. If the dye is drawn toward a specific point rather than dispersing naturally, water is escaping there.

For Pool Maintenance Camberwell residents dealing with older concrete pools, ground movement and tree root intrusion are particularly common causes of shell cracking — something worth keeping in mind if you have large established trees near your pool.

If the leak stops when the pump is off but continues when it is running, the issue is likely in the return lines or fittings under pressure. If it leaks regardless, the problem is almost certainly in the shell.

Customer Review

Lachlan Whitmore, Camberwell VIC

"I noticed my pool was losing about 10 cm of water every week and assumed it was just the heat. After months of topping it up, I finally called Green Pool Cleaning for help. The team came out, ran a full inspection, and found a hairline crack near the main drain fitting that I never would have spotted on my own. They walked me through the whole process and had it sorted quickly. What really stood out was how thorough they were — they also checked all my equipment connections while they were at it. My water bill has already come down and the pool is holding its level properly for the first time in ages. I would not hesitate to recommend Green Pool Cleaning to anyone dealing with unexplained water loss. Brilliant service from start to finish."

Repair Options: What Are Your Choices?

Repairs depend entirely on where and how severe the leak is.

Epoxy and putty fillers work well for small surface cracks in fibreglass or concrete pools and can often be applied underwater, meaning you do not need to drain the pool.

Skimmer box sealant — If the leak is around the skimmer or return fittings, a two-part pool putty or hydraulic cement is typically used to reseal the area.

Pipe repair — Underground plumbing leaks are best handled by a professional with pressure testing equipment. Attempting to dig and repair pipes without proper diagnostics can cause more damage than the original leak.

Liner replacement — For vinyl-lined pools, a patch kit can fix small tears, but widespread damage or a liner that has become brittle usually means full replacement.

Always address a leak promptly. A small crack left untreated can worsen with ground movement, particularly over winter, and a plumbing leak left unattended can erode the soil beneath your pool — a far more expensive problem to fix.

Conclusion

A leaking pool does not fix itself, and the sooner you act, the less it costs you in water, chemicals, and potential structural repairs. Start with the bucket test to confirm a leak is present, then methodically work through the shell, fittings, and plumbing to identify the source. For minor surface cracks and fitting leaks, a confident DIYer can often handle the repair with the right products. For anything involving underground plumbing or significant shell damage, bring in a professional who can pressure test and diagnose the system properly.

Regular pool inspections are the best way to catch problems early — before a hairline crack becomes a structural issue or a slow drip turns into a flooded yard. A well-maintained pool holds its water, holds its chemistry, and lasts far longer with less intervention. If your pool is losing water and you are not sure where to start, reach out to a qualified local pool specialist who can give you a clear diagnosis and a practical repair plan.