Waterproofing swimming pools

Waterproofing swimming pools is a critical component of the construction works required when building a pool. Historically, the trade of “waterproofing” didn’t exist. Certainly within the swimming pool industry, no specific specialised trades were ever employed to waterproof the structure of the pool. Instead, in-ground pool builders relied on:

  • the density and thickness of the concrete pool shell
  • the relative impermeability of the surface coatings applied to the concrete pool form
  • the epoxy seals and expandable foams to seal around penetrations (pipes, etc).

It’s probably best if I explained the mechanisms by which swimming pools leak before going into waterproofing methods

Most people imagine a pool leak in a swimming pool to be related to the failure of plumbing lines. Although this is sometimes the case, it is uncommon and easily fixed due to:

  • the widespread use of pipe pressure testing equipment to check for failed lines
  • the use of mini excavators to excavate the pluming lines to fail safe depths.

Pools also leak through “penetration leaks”. Simply, this is when water leaks out of the pool concrete form around the pipe or fitting penetration. Pool builders try to mitigate these type of leaks through applying epoxy collars and swell-able water stops. This works really well when correctly implemented.

The other type of water leak in a swimming pool and by far the hardest to fix is a “structural leak”. In this type of leak, water leaks through the concrete form of the pool shell at a slow and often undetectable rate. Most people aren’t even aware of having a “penetration or structural leak” in their swimming pool. Unless they can visually see a buildup of water on an exposed part of the pool, it is difficult to notice a leak.

This pool captures the modern design brief, built on the property boundary as well as the residence boundary and in full view from all living areas it abutts. It’s a showstopper, which relies on a modern in-floor cleaning system to keep it clean - as it can only be accessed from a single paved entry side.

Leaks in Older Swimming Pools

Past building practices meant that nearly every swimming pool shell was built in-ground and was fully concealed within the excavation. A penetration or structural leak in an in-ground pool, built as such, would be undetectable. It is integral with modern building styles of elevating pools and building pools within apartments that the pool is waterproof. In these builds, even a small leak will show up in plaster works or the walls of the levels immediately below the pool. Hence, the present need for a specialist trade and methods in waterproofing pools.

Preventing Leaks

At Momentum Pools we mitigate water loss via swimming pool leaks through the following best practices:

  • Plumbing leaks – We pressure test pipes and use our own excavator to dig trenches so they are at a safe depth. We also locate our pool plumbing lines near the pool shell and try to limit all services being enclosed in single service trench. Finally, we often back-fill over our plumbing lines with ¼ minus screenings or friable sand.
  • Penetration leaks – we fit epoxy collars around all our pipes and penetrations using a thixotropic plural component epoxy such as “ferrope”. We also use swell-able water stops when needed.
  • Structural leaks – we fit a 2 component polyurethane sprayed membrane, such as “Rhino Linings Tuff Stuff.” This is a practically indestructible and completely impermeable membrane lining. We have our own spray rig to fit these liners and have 2 specially trained staff who have completed the Rhino training course. Please note –  this is a highly specialised and consequently expensive process. It is best suited to critical waterproofing applications in apartment buildings, etc. where even a small water loss forms a critical problem.

We don’t fit membranes when a pool is to be built in a traditional fashion, fully encased within an earth excavation. This is because the small water loss of a few litres a day (if at all) is minuscule and not worth the expense of fitting an expensive membrane lining to the pool form.

We often fit very dense 3:1 render mixes with polymer modified render linings to our pool forms. This is part of the tiling process. This creates a near impenetrable barrier to water loss, although small leaks through such cementitious linings are a low possibility.

Important Points

  • Pools can and do leak. Your pool builder should state in the contract/quote some of the methods employed to prevent water leaks
  • The only way of guaranteeing no water leaks is to fit a whole structure membrane lining of the type. We use “Rhino Linings Tuff Stuff” to ensure this in appropriate jobs.
  • If your pool builder tells you he has “never had a leaking pool” he is either in denial or telling you what you want to hear
  • Do an evaporation test to work out if your pool leaks or not. Contact Momentum Pools and we will guide you through the process on how to go about it