Pools lose water two ways, evaporation and leaks, and the first job is always working out which one you are dealing with. On the Gold Coast, an uncovered pool can lose a surprising amount to evaporation in summer, several millimetres a day in hot, windy weather, which fools plenty of owners into thinking they have a leak when they do not, and reassures others that everything is fine when they are actually losing water through a crack. This page walks through the free checks that sort that out, where pool leaks usually hide, and when it is time to bring in someone with the right gear. Since pool owners often also ask about heating, our guide to pool heating on the Gold Coast is worth a look while you are here.
First, rule out evaporation with the bucket test
The bucket test is free, it takes two minutes to set up, and it is the single most useful thing you can do before spending money. It works because evaporation affects a bucket of pool water and the pool itself at the same rate, so it cancels evaporation out and shows you only the leak.
- Fill a bucket with pool water and sit it on a pool step so it is partly submerged, or on the deck right beside the pool.
- Mark both levels. Mark the water level inside the bucket and the pool water level outside the bucket, using tape or a marker. Get them right on the line.
- Turn the pump off and do not top up or swim for the test period.
- Wait 24 hours, then compare. If the pool has dropped the same amount as the bucket, you are only losing water to evaporation, no leak. If the pool has dropped noticeably more than the bucket, the extra loss is a leak.
Run it over a still, dry day for the cleanest result, and repeat it once to be sure if the difference is small. As a rough sense of scale, normal Gold Coast summer evaporation is in the range of five to ten millimetres a day, so loss well beyond that, especially if it continues regardless of weather, points to a leak.
The pump on versus pump off clue
Here is a useful refinement once the bucket test confirms a leak. Run the test again, but this time note whether the pool loses water faster with the pump running or with it off. A leak that is worse with the pump running is usually on the pressure side, the return plumbing pushing water out under pressure. A leak that is worse with the pump off is often on the suction side or in the shell itself, draining out under the pool's own weight. It is not a perfect rule, but it points you at the right half of the system before anyone starts digging.
Equipment pad versus the shell and plumbing
Pool leaks fall into two broad camps, and they are very different jobs.
The equipment pad, start here because it is the easy win
The equipment pad is the pump, filter, chlorinator or salt cell, heater if you have one, and all the visible valves and plumbing connecting them. It is above ground and you can see it, which makes it the easiest place to find a leak and the first place to look. Walk the pad while the pump is running and check for:
- Drips or spray at the pump, around the filter, at the multiport valve, and at every union and fitting.
- A wet patch under the pad that never quite dries out, or constant dampness around the base of the pump or filter.
- Crusty white mineral deposits on fittings, which are the dried residue of a slow leak that has been weeping for a while.
- Weeping at the filter clamp or the pump lid O-ring, both common and usually a cheap seal or fitting fix.
A good proportion of pool leaks are right here on the pad, and these are the most fixable. A perished O-ring, a cracked union, a weeping valve or a loose fitting can leak a meaningful amount of water and is often a straightforward repair.
The shell and underground plumbing, the harder camp
If the pad is dry, the leak is likely in the pool shell or the buried plumbing, and this is where it gets harder. Suspect areas include:
- The skimmer box, particularly where it joins the pool shell. Cracks at the throat of the skimmer are a very common pool leak.
- Return inlets, lights and fittings set into the wall, where the seal around the fitting can fail.
- Cracks in the shell, in the render, the fibreglass or the tiles and grout, sometimes from ground movement.
- The underground return and suction lines running between the pool and the equipment pad, which can develop leaks you will never see from the surface.
The dye test for shell leaks
Once you suspect the shell, a dye test helps pinpoint the spot, and it is another free DIY check. You need leak-finding dye or even ordinary food colouring, and a still pool, so turn the pump off and let the water settle completely with no movement.
- Get the water dead still. Any current will move the dye and ruin the test, so wait until the surface is glassy.
- Release dye slowly right next to a suspected crack, the skimmer throat, or around a light or return fitting. Squeeze it out gently so you do not create your own current.
- Watch the dye. If there is a leak at that spot, the escaping water draws the dye into the crack or fitting like a thread being pulled in. If the dye just drifts and disperses, that spot is sound, move on to the next suspect.
Work methodically around the skimmer, the returns, the lights and any visible cracks. The dye test is slow and patient work, but on a shell or fitting leak it can pin the exact spot for free.
Other clues worth noticing
- Where the water settles to. If the pool always drops to the same level and then stops, the leak is at that level, often a skimmer or a return fitting. If it keeps dropping past every fitting, suspect the main drain or a plumbing line.
- Soggy ground or settling around the pool, paving that has lifted or sunk, or a constantly wet patch in the garden near an underground line.
- An auto-fill that runs constantly. Many Gold Coast pools have an auto top-up. If it is forever running, it may be masking a leak, or the auto-fill valve itself may be stuck open and overfilling, which we cover on why is my water bill suddenly high.
- Air in the system. Air bubbles at the returns or the pump losing prime can indicate a suction-side leak drawing air in as well as letting water out.
When to bring in the gear
If the bucket test confirms a leak but you cannot find it on the pad or pinpoint it with dye, the leak is hidden in the shell or the underground plumbing, and that is specialist work. The same detection principles we use for house leaks apply, a pressure test on the pool's suction and return lines proves whether the underground plumbing is losing water and which line it is, and acoustic equipment can listen for an underground pipe leak. We explain that listening method on how does acoustic leak detection work. Pinpointing a buried pool line before excavating saves you from digging up the whole run on a guess.
One honest note on scope, structural pool work such as resealing a cracked shell, re-rendering or fibreglass repair is a pool specialist's trade. Where the leak is in the pool plumbing, the pad, the buried supply and return lines, the fittings and the connections, that is plumbing, and that is what we handle. If your test points at the plumbing side, our burst pipe repair service covers the failed-line work, and we will tell you plainly if part of the job is better suited to a pool builder.
Why a pool leak is worth chasing down
A leaking pool is not just topping itself up on your water bill, though that adds up fast, hundreds of litres a day on a decent leak. Water escaping from the shell or an underground line erodes the ground around and beneath the pool, which over time can undermine the structure and the surrounding paving. A leak that lets air into the suction side also makes the pump work harder and run hot. Finding and fixing a pool leak early is far cheaper than dealing with what an ignored one does to the ground and the equipment.
What to do next
Do the bucket test first, it costs nothing and tells you whether you have a real problem. If it confirms a leak, check the equipment pad, then dye-test the shell and fittings. If those free checks do not find it, the leak is hidden and it is time to get us in to pressure-test the plumbing and track it down properly. Get in touch and we will work through it methodically, find the leak on the plumbing side, and quote the repair honestly. If a pool line has let go and is dumping water fast, treat it as urgent and call our emergency plumbing service.