My New Pool Is Leaking | How to Tell and What to Do

Name: comparepoolquotes
Price range: $$$

Do the bucket test before you call anyone or pay for leak detection. An uncovered Australian pool loses around 7mm of water a day through summer to evaporation alone, so a falling level proves nothing. If the pool drops more than a bucket standing in it over 24 hours, you have a leak — and on a new concrete or fibreglass shell that is a defect, with a 6 year 6 month rectification window in Queensland.

The short answer

Evaporation is the usual answer. SPASA puts an uncovered pool at around 7mm a day over summer, at no cost to anyone but your water bill.
The bucket test compares the pool against a bucket in the same weather, so it needs no threshold, no inspection and no equipment.
Run it twice — once with the filtration pump running, once with it off. Loss only when the pump runs points at the plumbing, not the concrete shell.
A leaking shell is treated as a structural defect in Queensland, and the QBCC gives cracks in a pool shell as an example of defective work.
That matters for deadlines: structural gets years, non-structural gets 12 months from completion. Do not sit on it.

What the bucket test result actually tells you
Result over 24 hours	What it means	What to do next
Pool and bucket drop by the same amount	Evaporation. Normal, and worse in wind, heat and low humidity	Nothing. A cover cuts evaporation by 90–95%
Pool drops noticeably more than the bucket, pump running and off	A leak in the shell, the fittings or the structure	Report it to the builder in writing, dated, with the test result
Pool drops more only when the pump is running	Pressure-side plumbing or a return line	Report it — but say so, because it changes what gets dug up
Pool drops more only when the pump is off	Suction-side plumbing, skimmer or main drain	Report it with the same detail
Wet patch, sinking paving or soft ground beside the pool	Possible underground line or shell leak	Report immediately, photograph it, and stop topping up so the level can be read

First, prove there is a leak. It takes a bucket and 24 hours

The bucket test is the standard method leak-detection services use, and the reason it works is that it removes the guesswork about weather. Fill a bucket with pool water, stand it on a step so it is partly submerged and at the same temperature, mark the water level inside the bucket and the pool level outside it, and come back in 24 hours with the pump and any water features off.

Both levels will have dropped, because both are evaporating in the same air. If the pool has dropped further than the bucket, the difference is your leak. If they match, you do not have one.

Then run it again with the pump on its normal cycle. Comparing the two results is what tells a plumber where to look, and arriving with that answer already in hand is what keeps an investigation from becoming an excavation.

Do not top the pool up during the test, and do not run it in rain.

Why the number on its own means nothing

Owners regularly report a "leak" of a few centimetres a week that turns out to be an ordinary Australian summer. SPASA puts an uncovered average backyard pool at around 7mm of water a day through the summer months — roughly 5cm a week, from evaporation alone, with nothing wrong at all.

Evaporation is driven by wind, water temperature, humidity and sun, so it swings day to day and pool to pool. That is exactly why an absolute threshold — "more than X mm a day is a leak" — is unreliable advice, and why the bucket test is the right method: it measures your pool against your weather on your day.

For scale, a pool cover reduces evaporation by 90–95%, saving about 3,000 litres a month. If your only complaint is the top-up bill rather than a suspected fault, that is the fix. See what a pool costs to run per year.

If it is a leak on a new pool, it is a defect — treat it as one

On a pool that is months rather than decades old, a genuine leak is defective building work, not maintenance. The QBCC gives cracks in a pool shell that let water leak through the concrete as an example of defective building work, and leaking is treated in the structural category rather than the cosmetic one.

That classification is worth more than it sounds, because the deadlines differ enormously. In Queensland a direction to rectify may be issued within 6 years and 6 months of the work being completed for a structural defect, but the QBCC will only consider one within 12 months of completion for a non-structural defect. A request for a direction should be made within 12 months of you becoming aware of the problem.

So: report it in writing the day the bucket test comes back positive, with the test result and photographs, and keep the dated email. What to do when the builder does not fix the defects covers the escalation path and the deadline table.

What not to do while you are waiting

Do not empty the pool. A drained concrete shell can float or crack in wet ground, and a fibreglass shell can distort. If someone tells you to drain it to find the leak, ask them to put the advice and the responsibility in writing first.

Do not seal anything yourself before the builder has inspected. A patched crack is harder to attribute later, and attribution is the whole argument.

Do keep the water balanced and keep topping up outside the test window — an unbalanced pool gives a builder an argument about cause, and a barrier around a pool nobody is maintaining is still your obligation. If the pool is unusable and you are weighing rectification against replacement, get independent quotes: free pool quotes and what should be in a pool quote.

Common questions

How much water loss is normal for an Australian pool?

SPASA states that uncovered, an average-sized backyard swimming pool loses around 7mm of water per day during the summer months, and that a pool cover reduces evaporation by 90–95%, saving 3,000 litres a month — see SPASA's pool water savings techniques. Evaporation varies with wind, heat and humidity, so compare against a bucket rather than against a published number.

Is a leaking pool shell covered by the builder?

On a recently built pool it is normally defective building work rather than wear. The QBCC cites cracks in a pool shell that let water through the concrete as an example of defective work, and leaking falls in the structural category, which carries the longer statutory window.

Should I call a leak detection service or the builder first?

The builder first, in writing, if the pool is new — you want the defect reported inside the statutory window and you do not want to have paid for someone else to open up their work. A detection service is worth it once the builder disputes there is a leak at all.

Can I do the bucket test on a pool with an automatic top-up?

Not reliably. Turn the auto-fill off for the test, or it will quietly replace exactly the water you are trying to measure. Same for a water feature — anything that moves water changes the result.

Sources

General information only, current at 2026-09-10. Pool rules differ by state and by council, and penalty amounts are updated regularly. Confirm your own obligations with your council or a registered inspector before acting.

“My new pool is leaking” — how to tell, and what to do