The 50-year-old water tower in Salaspis consists of a metal tank at the top for water storage. The existing waterproofing membrane from EPDM deteriorated over time and leakages appeared so a renovation became inevitable as it was planned to continue using the water tower. Here, the KÖSTER TPO Aqua 1.5 was chosen, which is a homogeneous thermoplastic polyolefin waterproofing membrane specially designed for drinking water structures. It complies with the hygienic requirements for potable water surroundings.