Pool losing water: how to tell where it goes and what to do
A falling water level does not mean the pool has a leak. Every pool loses water to evaporation, to swimmers and to the filtration itself. The useful question is a different one: is it losing more than normal, and where? Two simple tests almost always tell you, before you call anyone.
Evaporation or a leak?
As a reference, losing 2 to 3 cm of water a week to evaporation, use and filtration is considered normal (Momentos Piscina). In high summer it can be a good deal more: Meteored calculated that a 10 × 5 metre pool in Málaga would have lost between 335 and 428 litres a day to evaporation in the Julys of 2007 to 2009 (tiempo.com).
So the level on its own says nothing. It has to be compared with something that loses water to evaporation and nothing else. If what you can already see are cracks in the shell, how to tell each kind apart is in repairing cracks and leaks.
The bucket test
- Fill a bucket with water and stand it on the first step of the pool, so it has the same temperature and the same sun.
- Mark the water level in the bucket and on the pool wall.
- Run the pump as usual and wait 24 to 48 hours.
- Compare: if the pool dropped more than the bucket, there is a leak. If they dropped the same, it is evaporation.
As a rule of thumb, a difference of more than one centimetre in 24 hours between the pool and the bucket already points to a leak (Momentos Piscina).
Where is the water going?
With the pump on and off
Repeat the measurement twice: one day with the pump running and one with it off. The comparison says a lot (Momentos Piscina):
- More loss with the pump on: the leak is usually in the return circuit, the one that sends water back to the pool through the jets.
- Less loss with the pump on: it points to the suction circuit, the skimmers and the main drain.
- The same loss either way: most likely a crack or a fissure in the shell itself.
Where the level stops
Another clue is to let the level fall without topping up and see where it stops (Fluotechnik). If it settles at a given height, look at what is right there: the skimmer mouth, a light, a jet. If it does not stop, the loss is lower down, in the main drain, the floor or the shell.
What to do, depending on where the leak is
- In the pipes or the pump: it has to be found and repaired, which is a job for a leak technician or a plumber. A new pool lining will not fix it.
- In the skimmers, jets or lights: these are where leaks come back most often. They are sealed or replaced, and a relining job checks all of them.
- In the shell: cracks, chips, tiles coming off. Patching is usually temporary: one area is covered and the leak turns up next to it.
When reinforced liner is the answer
If the water is escaping through the shell or its fittings, the fix that does not depend on chasing each leak is to replace the lining with a continuous one. RENOLIT ALKORPLAN reinforced liner is laid over the prepared shell, hot-welded panel by panel, and creates a new, fully watertight surface. Skimmers, jets and lights are sealed in the same job. A residential pool takes 3 to 5 days and, done by a certified installer, carries a 15-year watertightness warranty.
What it involves, step by step, is on the page on reinforced liner in old pools. And if the question is what to replace the gresite with, we compare porcelain tile or reinforced liner.
We work from Chiclana de la Frontera across the whole province of Cádiz. If your pool is losing water, with the size of the shell and its current lining we will prepare a no-obligation quote.
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