Does a new pool finish stop a leak?

The short answer

A new finish, whether tiles or PebbleCrete, does not stop a leak. The finish is a surface layer. It may hide minor seepage through a porous shell for a time, but it is not designed to hold water back. Waterproofing is a separate system that sits beneath the render and the finish. Leaks also come from places the finish does not cover or cannot seal: in our experience water most often escapes through pool light fittings whose conduits were run through the shell instead of being brought up properly above water level, as well as through buried pipes, construction joints, balance tanks or an overflow edge set so high that water runs into the terrace joint. Find and repair the leak first.

Why refinishing over a leak goes wrong

If the leak is still active, water keeps escaping behind the new surface. The ground around the pool can keep softening, terraces can be undermined, and water moving through cracks or behind a loose finish can lift or stain the new surface. A new finish can also make a leak harder to find, because it covers up the signs on the surface. Often you then end up draining the pool again to do what should have been done first. Draining a pool whose surroundings are waterlogged also carries its own risk: groundwater pressure from outside can damage the shell or lift a new finish, so the timing of any draining needs care.

Putting the work in the right order

Tracing the leak and waterproofing are covered by our leak repair and waterproofing service. We work through likely causes and test them using imported fluorescent dye kits and a special torch, and by pressure testing the pipework, though we cannot promise to find every fault without excavation or opening parts of the structure, and hidden problems can emerge in stages when a pool's history is unknown. You may also want to change the layout, add steps or a shallow ledge (Baja shelf or tanning ledge), or renew the surface. Pool remodelling can bring this together as one project, planned around your season or bookings, so the pool is drained as few times as possible.

• Testing likely causes, usually with water in the pool: fluorescent dye and a special torch at suspected points, and pressure testing of the pipework
• Repairing the cause: replacing leaking lights (with electrical work agreed with your electrician or engineer), re-laying pipes, fixing joints or lowering the overflow level
• Waterproofing the shell or tank where needed, including tank-in-tank rebuilds for balance tanks or, in difficult cases, the pool itself
• Renewing the surface once the leak has been dealt with

What to send us for a first discussion

• Photos of the pool, the overflow, the balance tank and the pump room
• Your location in Phuket or elsewhere in Thailand
• How much the water level drops with the pump on and off, and what you have noticed
• Any past repairs or earlier refinishing

Further reading

• Renovating an older pool without demolition