Often water tanks have special requirements on the waterproofing system, such as being elastic with crack-bridging capabilities. Other factors may be pollutants in the water, as is common with skimmer tanks. A system including KÖSTER 21 is exactly the right choice for these types of environments.

Waterproofing tanks with mineral based products has a long history of successful applications. Various design requirements such as water-tightness, durability, mechanical and chemical resistance must be considered, as well as certification for use in drinking water environments. The KÖSTER NB 1 system for these types of constructions meet and exceed all of these requirements.

Waterproofing for drinking water storage structures and tanks must not only remain watertight for many years, but must also meet all sanitary requirements. KÖSTER TPO Aqua is a homogeneous thermoplastic polyolefin waterproofing membrane for drinking water structures. KÖSTER TPO Aqua complies with the hygienic requirements for potable water surroundings according to the German DVGW Worksheet W 270 and the KTW guideline.

The membrane is mechanically fastened, which leads to low preparation requirements on the substrate. The substrate must be as smooth as possible and free of edges, depressions, and other defects that can mechanically damage the membrane. Edges must be ground and depressions and holes filled and leveled with KÖSTER Repair Mortar. Soil substrates must be excavated down to a solid layer and mechanically compacted. In interior corners on concrete, masonry, or other mineral substrates  and  structures,  install  a  fillet  made  of  KÖSTER  Repair Mortar  Plus  on  the  wall-floor-junction  approx.  24 hours prior to the
application. For extra mechanical protection of the membrane, a geotextile mat (approx. 500 g/m²) can be installed on the bottom of the reservoir before installing the KÖSTER TPO Aqua.

Overlaps are connected by hot air welding, which creates a homogeneous, durable connection.
For large areas, the Leister Automatic Welder Varimat V2 hot air machine is used. Details and non-accessible areas are welded with the Leister Hot-Air Hand Tool with a 40 mm nozzle.

Details such as terminations, penetrations, and flashings are job-site specific and require special care. Always adhere to the specifications in the respective Technical Guidelines.