Evaporation
Sun, heat and wind across the surface. Established or ruled out with a bucket test before anything is priced.
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Pool leak detection in Durban has to answer one question before all the others: is it leaking, or is it evaporating? There is a free test that settles it, and it is worth running before you pay anybody, including us.
Tell us roughly how much it drops and whether that changes when the pump runs. Those two details narrow a pool leak faster than anything else you can tell us.
Six places, found six different ways. The first one is not a fault at all, and it is the most common answer.
Sun, heat and wind across the surface. Established or ruled out with a bucket test before anything is priced.
The conduit behind a pool light is a classic path for water to leave the shell without any visible crack at all.
Where a moulded fitting meets the shell. Two materials, two expansion rates, and a Durban temperature swing.
Suction and return lines between pool and plant, pressure tested individually so the failed line is identified.
Located with dye testing at suspected points while the pool stays full, rather than by draining it to look.
An automatic filler hides a leak completely by replacing it. The pool looks fine and the meter keeps turning.
Pool leak enquiries have an unusual property: a good proportion of them are not leaks. Durban is warm, bright and frequently breezy, and all three of those drive evaporation hard. A pool that quietly drops a bit each week through summer is very often doing exactly what physics requires of it, and the owner has been worrying about a fault that does not exist.
Wind is the part people underestimate. Heat and sun matter, but moving air across a water surface carries away the saturated layer sitting just above it and lets the next lot evaporate, so an exposed pool on a windy afternoon loses substantially more than a sheltered one in the same conditions on the same day. Which is why two neighbours with identical pools can reach quite different conclusions about whether theirs is leaking.
The bucket test separates the two properly and costs nothing at all. Put a bucket on the second step so it sits partly submerged, fill it with pool water until its inside level matches the pool's, mark both, and leave it 24 hours with the pump off and nobody swimming. Sun, heat and wind act on the bucket and the pool identically. If both drop by the same amount, that is evaporation and you are done. If the pool has dropped further, the difference is a genuine leak and you now have a daily figure for it.
There is one thing that defeats this test and it is worth knowing about, because it is also the reason some pool leaks run for years unnoticed. An automatic top up valve keeps the level constant by replacing whatever is lost. The pool looks perfect, nothing ever appears wrong, and the only evidence is a water bill that has been slightly too high for longer than anyone can remember. If you have one, close it for the 24 hours of the test.
Do the bucket test before you contact anybody, and do it with the pump off and the top up valve closed. If the levels match, you have saved yourself the cost of a trace and the answer is a pool cover rather than a plumber. If they do not, tell us the difference in millimetres and whether it gets worse when the pump runs, and that pair of numbers will have narrowed the search before anyone arrives.
Twenty four hours, no cost, and it answers the only question that matters first.
Pool full, paving intact, and the location known before anything is opened.
If the bucket test has not been done, that happens first, because a trace on a pool that is not leaking helps nobody.
Whether the loss changes with the pump running separates the two, and each gets a different method after that.
Suction and return tested individually, so the failed line is identified rather than the whole run being dug up.
You get the location and the repair price as separate things, and the pool stays full throughout the finding part.
Cost first, then the test that tells you whether you need to spend anything at all.
It is priced as a job, not a call-out, because locating a pool leak takes pressure testing equipment and time on site. A domestic pool is usually a half day, against the trade's published guidance of R450 to R850 an hour excluding VAT plus the call-out. Set that against the alternatives: draining and refilling a pool is expensive in water alone on a metered supply, and lifting paving to find a pipe you have not located is considerably worse. Run the free bucket test below first, because it sometimes ends the matter.
The bucket test, and it costs nothing. Put a bucket on the second step so it is partly submerged, fill it with pool water to match the pool's level, mark both levels, and switch the pump off for 24 hours with nobody swimming. Evaporation affects the bucket and the pool equally. If both have dropped the same amount, you are watching evaporation and you do not have a leak. If the pool has dropped more than the bucket, the difference is your leak and you now have a number for it.
More than people expect, because this is a warm, sunny, often windy coastal climate and all three of those drive it. Wind matters more than most people realise: a breeze across the surface lifts the rate considerably, which is why an exposed pool loses noticeably more than a sheltered one on the same day. A pool that drops a little each week in summer is usually behaving normally. That is exactly why the bucket test is the first step, because it separates a climate you cannot fix from a leak you can.
If it does, that is genuinely useful information and it narrows the search immediately. A leak that worsens with the pump on is on the pressure side, meaning the return plumbing after the pump, which is under positive pressure only while it runs. A leak that is worse with the pump off is often on the suction side or in the shell itself. So note which it is before contacting anybody, because that one observation can halve the time a trace takes and therefore what it costs.
In roughly this order: the light niche and its conduit, the skimmer where it meets the shell, the return and suction fittings, cracks in the shell or failed fibreglass, and the buried plumbing between the pool and the plant. The joints between different materials are the weak points, which is why the skimmer and the light are so common: they are places where a fitting is bonded into a shell, and the two expand and contract differently in Durban's temperature swing.
Neither, to locate it. Pressure testing the plumbing lines individually shows which line has lost integrity while the pool stays full, and dye testing at the suspected points on the shell shows exactly where water is moving. Draining or opening up comes after the location is known and only where the repair has to happen. Anybody proposing to drain a pool as a diagnostic step rather than as part of a located repair is proposing something expensive that will not tell you very much.
Usually, and the arithmetic is worth doing rather than guessing at. Work out the daily loss from the bucket test in millimetres, multiply by the surface area to get litres, and price that against your water tariff. A leak that sounds trivial in millimetres can be hundreds of litres a day on a reasonably sized pool, and it runs every day indefinitely. Against a one off location and repair, the payback is often shorter than people assume, and that is before the damage a persistent leak does to what is under the pool.
Very commonly, and it is worth eliminating one before paying to investigate the other. An automatic top up valve makes this worse by design: it quietly replaces whatever leaks out, so the pool level never drops, nothing looks wrong, and the meter runs all year. If you have a top up valve, close it for the 24 hours of the bucket test. If the bill is climbing and the pool checks out clean, the next step is leak detection on the house supply.
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Losing pool water in Durban? Run the bucket test first, then tell us the difference and whether the pump makes it worse.