In this article
A floor leak is one of the hardest pool leaks to detect. The floor is far from view and always under water, and the escaping water goes straight into the soil beneath the pool instead of appearing on a wall or in the plant room. The leak can therefore run for a long time before the owner notices, and during that time the soil, concrete and waterproofing are all affected.
The good news is that a floor leak leaves signs, some in the water, some on the floor and some around the pool. If you know what to look for, you can catch it early and call for specialist detection at the right time. This article focuses on the floor. If you suspect the walls, we cover them in a separate guide.
Why pool floors leak
- Soil settlement or movement: poorly compacted soil, or soil whose moisture changes over time, can shift slightly and open fine cracks in the floor.
- Failed waterproofing under the tiles: the floor membrane carries the full weight of the water, and any weakness or ageing lets water through.
- The main drain: the area around the main drain is one of the most common leak points because concrete, pipes and waterproofing meet there.
- Construction joints: if the floor was poured in stages and the joint was not treated properly, it becomes a path for water.
- Thermal stress: draining the pool, exposing the floor to sun and refilling with cooler water causes movement that can open hairline cracks.
Early signs you should not ignore
In the water
- A steady drop in level even when nobody swims, faster than evaporation would explain.
- The same rate of loss with the pump on or off. Pipe leaks usually change with the pump running, while floor leaks continue either way.
- Needing to add more water and chemicals than usual to keep balance.
On the floor
- Fine cracks or dark lines in tiles or grout, especially in the deep end.
- Slightly raised tiles, or tiles that sound hollow when tapped with a tool while the level is lowered.
- Dust or sand repeatedly gathering at one spot, possibly drawn towards a crack.
- Grout discoloured in one area only.
Around the pool
- Sinking deck tiles or paving.
- Damp soil or unusually lush grass on one side.
- Damp in nearby rooms or a basement.
How to inspect the floor yourself
This does not replace specialist detection, but it gives the technician useful information:
- Pick the right moment: a calm morning with the pump off long enough for the water to settle.
- Use goggles or a mask and look closely at the floor, especially around the drain, corners and deep end.
- Look for lines and cracks and photograph anything you see to track changes.
- Watch suspended particles: if fine particles drift towards one point while the water is still, that strongly suggests suction.
- Log the level daily with a mark on the tile or a bucket test.
The role of soil and ground movement
Soils in Riyadh and across the Kingdom vary between sandy, clay and rocky ground, and each reacts differently to water. Leaking water can wash sandy soil away over time and create voids under the floor. Clay swells when wet and shrinks when dry, pressing on the concrete and causing cracks. A floor leak is therefore not just a water problem. If it continues it can become a structural one, and the repair may need more than sealing a crack.
Telling a floor leak from other sources
| Observation | Points to the floor | Points elsewhere |
|---|---|---|
| Loss with pump off | Continues at the same rate | Slows or stops, possibly pipes |
| Level where loss stops | Keeps dropping | Stops at a fitting or wall crack |
| Where damp appears | Sinking paving or low-lying damp | Near the plant room or pipe route |
For a detailed comparison, read how to tell whether your pool leak is in the floor or the walls.
What to do once you see the signs
- Do not drain the pool yourself. Draining loses the chance to locate the leak and exposes the floor to pressure and heat.
- Record your notes, photos and daily loss rate.
- Request specialist detection covering pipe tests and floor checks with dye or suitable equipment.
- Once the source is found, the technician decides whether a local repair is enough or the floor needs draining and re-waterproofing.
YAM Pools starts with a site visit and inspection of the pool and pipework, then explains the leak source and repair method in a written quotation, with a written warranty on workmanship and waterproofing. We serve Riyadh and all cities of Saudi Arabia.
Frequently asked questions
Could the loss just be evaporation?
Yes, especially in summer and wind. A bucket test compares pool loss with bucket loss under the same conditions. If the pool loses clearly more, there is a leak.
Why does the level not stop at a certain point?
A floor leak sits at the lowest point, so water keeps dropping. Wall or fitting leaks usually stop at the level of the crack or fitting.
Does a floor leak always mean draining the pool?
Not always. Some cracks can be sealed under water with specialist products, but wide or deep leaks usually need draining and re-waterproofing of the area.
Can a floor leak affect the house?
If it continues for long it can affect soil, foundations and nearby paving. Early detection protects both the pool and the building.
