How to waterproof a swimming pool: liner, paint or polyurea

A pool shell isn't waterproofed with a single system valid for every case: there are three options with very different price, durability and technical demands, and choosing the wrong one ends up costing more in the medium term.

PVC liner: lasts for years, but it can be punctured

The liner lines the whole pool shell with a sheet welded on site. It lasts for years, but can be punctured and should be checked periodically. The thickness changes its resistance:

• 0.75 mm: standard.
• 1.5 mm, reinforced: withstands abrasion and sharp objects on the pool floor better. In public or very busy pools, don't go below the reinforced thickness.

It is bought with a 10% margin for welded overlaps.

Waterproofing paint: cheaper, with periodic maintenance

Waterproofing paint is applied directly to the concrete or masonry shell, and needs repainting every few years — it is the cheapest of the three solutions, in exchange for less durability. Always apply it to a shell that is completely empty, clean and dry: painting over residual damp or lime residue is the most common reason the paint lifts after a few months.

Worked example: for 40 m² of shell with 2 coats: (40 × 2) ÷ 6 ≈ 13.3 litres. This is the same calculation the PresupuestoYa calculator applies automatically for the Waterproofer trade.

Sprayed polyurea: the high-demand option

Sprayed polyurea is a system of extremely high mechanical and chemical resistance, applied hot with specialist equipment, curing in seconds. It is used in industrial tanks and high-demand pools. It's not an application for beginners: it requires high-pressure hot-spray equipment and specifically trained staff. If you don't have that equipment, subcontract this item instead of trying to improvise it.

Frequently asked questions

What liner thickness do I choose for a communal pool? 1.5 mm reinforced — in public or very busy pools it's best not to go below that thickness because of the greater abrasion and risk of sharp objects.

Why does the waterproofing paint on a pool lift after a few months? Almost always because it was applied to a shell with residual damp or lime residue, without making sure it was completely empty, clean and dry before painting.

Can I apply sprayed polyurea myself without specialist equipment? It isn't recommended: it requires high-pressure hot-spray equipment and specific training. If you don't have that equipment, the right thing is to subcontract the item.

Conclusion

Choosing between liner, paint and polyurea depends on the real use of the pool and the budget available for long-term maintenance, not just the initial cost. Preparing the shell well before applying any of the three systems is what decides whether the work lasts for years or has to be repeated after a few months.