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 and 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; as well as epoxy seals and expandable foams to seal around penetrations (pipes, etc).

Before I go into more detail on waterproofing practices, probably best if I explained the mechanisms by which swimming pools leak.

Most people imagine a pool leak in a swimming pool to be related to the failure of the plumbing lines. This is sometimes the case – though the widespread use of pipe pressure testing equipment to check for failed lines; and the use of mini excavators to excavate the pluming lines to fail safe depths means plumbing line failures are uncommon and easily fixed.

Pools also leak through “penetration leaks”, whereby water leaks out of the pool concrete form around the pipe / fitting penetration that passes through the concrete form. Pool builders try to mitigate these type of leaks through applying epoxy collars and swellable water stops – which 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 imperceptible 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 form.

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

Building practices of years past, meant that nearly every swimming pool shell was built in the ground and was fully concealed within the excavation. A penetration or structural leak in an in-ground pool, built as such, would be imperceptible; water losses of a few hundred litres a day relative to the pool volume of 70 thousand litres would be inscrutable. Modern building styles of elevating pools above the ground and building pools within apartment buildings, etc. mean even a small loss of a few litres of water a day will show up in plaster works etc. on the levels of the residence immediately below the pool structure. Hence, the present need for a specialist trade and methods for 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 into being enclosed in single service trench; as well 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”. Swellable water stops are also employed, when needed.
Structural leaks – we fit a 2 component polyurethane sprayed membrane, such as “Rhino Linings Tuff Stuff”, a practically indestructible and completely impermeable membrane lining. We have our own $40,000 spray rig to fit these liners as well as 2 specially trained staff who have completed the Rhino training course. Please note –  this is a highly specialised and consequently expensive process best suited to critical waterproofing applications in apartment buildings etc. where even a small water loss forms a critical problem.

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

Often the very dense 3/1 render mixes with polymer modified render linings we fit to our pool forms as part of the tiling process create a near impenetrable barrier to water loss, although small leaks through such cementitious linings are a 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”
  • If your pool builder tells you he has “never had a leaking pool” he is either in denial or just telling you what you want to hear
  • Do an evaporation test to work out if your pool leaks or not – call Momentum Pools and we will guide you through the process on how to go about it