Perth water guide
The bucket test, step by step.
Five minutes to set up, a day to wait, and you know whether your pool is leaking or just losing water to the sun. Here is how to run it properly — and the printable one-pager to take outside.
Why a bucket settles the question
Every pool loses some water to evaporation, and in a Perth summer that can be a surprising amount. The problem is that a dropping water level looks identical whether the cause is the weather or a hole — you can’t tell them apart just by watching the tile line fall.
The bucket gives you a control. A bucket of pool water sitting in the pool loses to evaporation at the same rate the pool does, but it can’t leak. So if the pool drops more than the bucket, that extra loss isn’t the weather — it’s going somewhere. For the bigger picture of bills and the water rules, see Perth water rules, evaporation, and pool leaks.
The four steps
It costs nothing and needs only a bucket and some tape. Run it before you call anyone.
Float a bucket of pool water
Fill a bucket about three-quarters with water taken straight from the pool, and stand it on the top step so it sits partly submerged. Weight it with a brick if it wants to float. Using the pool's own water, at the pool's own temperature, means the bucket and the pool lose to the same sun and the same wind.
Mark both water levels
Mark the level inside the bucket and the pool's level on the skimmer or a tile, at the same moment. A strip of masking tape on each, with a pen line, is easiest to read a day later. Note the time.
Leave it a full 24 hours
Keep the pump running on its normal schedule, no swimming, and switch off any auto-fill so the pool can't quietly top itself up. Pick a window with no rain. Both the bucket and the pool now spend the same day losing water under the same conditions.
Compare the two drops
Come back at the same time the next day and measure how far each level fell. If the pool dropped about the same as the bucket, you are looking at evaporation. If the pool dropped clearly more than the bucket, the difference is water leaving the pool somewhere it shouldn't — a leak.
Reading the drop against the weather
The bucket already accounts for the weather for you — that’s the point of it. But the size of the gap is worth understanding. Above 38°C in a Perth summer, evaporation alone runs about 5–8mm a day, so even a healthy pool drops noticeably in a heatwave. Through a mild, still week it is a fraction of that.
A useful rule of thumb: a pool falling about a centimetre a day in mild weather is almost certainly losing water somewhere it shouldn’t. In a heatwave that same centimetre can be honest evaporation — which is exactly why the bucket sitting beside it matters. Trust the gap between the two levels, not the pool’s drop on its own.
Three ways the test goes wrong
If your result looks odd, it is almost always one of these.
Auto-fill left running
A float valve or auto-top-up quietly refills the pool as it drops, so the pool level barely moves and a real leak hides completely. Switch it off for the full 24 hours — this is the single most common reason the test reads clean when it isn't.
Rain, wind, or a swim
Rain adds water, wind speeds evaporation unevenly, and a swim splashes a measurable amount out. Any of the three throws the comparison. Pick a calm, dry day and keep everyone out of the pool.
Bucket and pool in different exposure
If the bucket sits in shade while the pool bakes in full sun, they evaporate at different rates and the test lies. Keep the bucket in the water on the step so both share the same sun, the same air, and the same temperature.
Take it to the poolside
We’ve put the whole test on a single printable page — the four steps, the weather guide, and the three mistakes to avoid. Print it, stick it on the shed wall, and run the test without a screen.
The test says leak. What now?
The bucket test tells you whether you have a leak, not whereit is. Finding where the water goes is the diagnostic: we measure the real loss against the day’s conditions, isolate the plumbing from the shell with a pressure test, trace any buried line with an acoustic ground microphone, and on Tier B dive the pool to inspect the shell and fittings at depth. You get a written report within 24 hours — where the water is going, the evidence, photos, and a repair quote where the leak is repairable.
Bucket test says it’s a leak?
Book a fixed-price diagnostic this week, or look at the two tiers first.