Pool leaks: step-by-step detection and repair

Signs of a leak

• You top up much more often than in previous years, in similar weather.
• Wet or sunken patches in the ground around the pool or above the pipe runs.
• Water on the plant room floor.
• Air bubbles from the return inlets, or a pump that loses its prime.
• Higher chemical use, because fresh water keeps coming in.
• Wrinkles or bulging in the liner that were not there before.

The first step is always the bucket test, which tells a leak apart from normal water loss. The procedure is described in detail in the guide to water evaporation.

Where it is: a simple logic

Do the test twice, once with the pump running and once with the pump off, for 24 hours each time. The comparison narrows the search a lot:

The logic is simple: when the pump is running, the return pipes are under pressure and push water out of any crack, while the suction pipes are under vacuum and draw in air instead of losing water.

Another clue is the height at which the level stops falling: if it stops at the bottom of the skimmer, the skimmer is the suspect; if it stops at the height of the return inlets or the light, look there. But do not let a liner pool drain down just to find out. If the level keeps dropping, top up and call a technician.

Point-by-point checks

Plant room

This is the easiest place to start. Check the joints, valves, the pump strainer lid and the pump shaft seal. One "hidden" spot is the multiport valve: if its internal gasket is worn, water flows to waste all the time, even in the filter position. Check whether water is running from the waste outlet or through the sight glass, where there is one. More on the layout in the pool plant room.

Inlets and gaskets

The pool fittings (skimmer, return inlets, main drain, lights) pass through the liner and are sealed with gaskets and screws. This is where most leaks in the pool shell appear. With the pump off and the water still, release a little special leak detection dye very close to the suspect spot: if a gap sucks it in, you have found the leak. A diving mask helps a lot.

The liner

Check corners, steps and the floor for holes from sharp objects, animal claws or cleaning tools, and confirm with the same dye.

Repair, and when you need a technician

A small hole in the liner can usually be closed with a PVC patch and an adhesive that works underwater, without emptying the pool; the steps are in liner repair. You need a technician when:

• the leak is at the gasket of a fitting or in a welded seam;
• the loss continues without any spot being found, so the buried pipework becomes the suspect;
• you see damp or subsiding ground next to the walls.

Water escaping under the liner can wash away the floor underlay and cause dips and wrinkles. Do not leave the check until the end of the season. If the liner is still under warranty, contact whoever installed it first, before any intervention.

Questions

See also