If you've been topping up your pool more than usual, you might be wondering whether you have a leak — or whether it's just the summer heat doing its thing. The truth is, a lot of pool owners live with a slow leak for months without realising it, simply because they can't tell the difference between evaporation and a genuine water loss problem.
The good news? You can figure it out yourself, at home, with no special tools. Here's how.
How Do You Know If It's Actually a Leak?
Before you start pulling apart your pool equipment, it's worth understanding what normal water loss looks like. Every pool loses water to evaporation — and the rate changes depending on the weather, your water temperature, wind exposure, and whether you use a pool cover. In Sydney's summers, a pool can lose a surprising amount of water just from evaporation alone.
The problem is, evaporation and a leak look exactly the same from the outside: the water level drops. That's why the first step isn't to go hunting for a crack — it's to confirm there actually is a leak in the first place.
The Bucket Test: Your First Step
The bucket test is the simplest and most reliable way to determine whether your pool is leaking. Here's how to do it:
- Fill a bucket with pool water and place it on one of the pool steps, partially submerged. The idea is that both the bucket and the pool are exposed to the same conditions — sun, wind, air temperature.
- Mark the water level inside the bucket and the pool water level on the side of the bucket or the skimmer box. Do this when the water is calm and still for the most accurate reading.
- Wait 24 hours, keeping the pump running as normal.
- Check the levels. Compare how much the bucket water dropped versus how much the pool water dropped.
- Same drop in both? No leak. What you're seeing is just evaporation.
- Pool dropped more than the bucket? Your pool is leaking.
It's a simple test, but the result is definitive. If the pool is losing more water than the bucket, something is wrong.
Pump On vs. Pump Off: Narrowing It Down
If the bucket test confirms a leak, your next step is to figure out roughly where it's coming from. You do this by repeating the bucket test — but this time, with the pump completely off for the full 24 hours.
Compare the two results:
- Water loss is higher with the pump running — the leak is likely in the plumbing system (pipes, valves, fittings, or the equipment pad).
- Water loss is the same whether the pump is on or off — the leak is likely in the pool structure itself (the shell, walls, or floor).
This one extra test narrows the search significantly, saving you — or a professional — a lot of time.
The Main Types of Pool Leaks
Pool leaks tend to fall into a few common categories. Knowing where to look makes the job a lot easier.
Structural leaks (shell and surface) Cracks in the pool shell, gunite, or fibreglass can develop over time due to ground movement, age, or impact. These are often visible on close inspection but can also be hidden below the waterline. A common sign is water loss that stays consistent whether the pump is on or off.
Fittings and light niches The fittings where your return jets, skimmer, and pool light are sealed into the pool wall are common leak points. The sealant around them degrades over time. These can be hard to spot visually but are often found during a professional dye test.
Plumbing leaks Underground pipes between the pool and the equipment can crack, corrode, or come apart at the joints. These often show up as wet ground near the equipment pad or along the plumbing run. The pump-on/pump-off test points strongly toward this type.
Equipment pad leaks The pump, filter, heat pump, and valves can all develop leaks at their connections or seals. These are usually the easiest to spot — look for water pooling near your equipment, drips, or mineral staining around fittings.
What to Do Once You've Isolated It
Once you have a rough idea of what you're dealing with, you have a few options.
If the leak appears to be at the equipment pad — a loose fitting, a weeping valve, or a worn pump seal — these are often straightforward fixes that a good pool technician can take care of quickly.
If the bucket test points to a structural issue or a plumbing leak, it's worth bringing in a leak detection specialist. Genuine leak detection specialists — not just general pool companies who offer it as a side service — use equipment like pressure testing and dye injection to pinpoint the exact location of a leak without unnecessary digging or guesswork.
Either way, acting sooner rather than later matters. Even a slow leak adds up fast. A one-inch drop in a standard pool can mean 500+ litres of water lost — and that's before you factor in the chemicals, the structural risk to the surrounding ground, and the long-term damage to your pool.
If you've run the tests and confirmed your pool is leaking, get in touch with the team at Sydney Pool Servicing. We'll help you track it down and sort it out properly.