The aim of this research is to investigate the innovative combination of water and membranes for temporary architectural applications. Water can be useful, as a construction material, for three different purposes. First of all, thanks to its thermal mass, it can be used as a medium for cooling down or heating up buildings ; secondly, water is uncompressible and, in combination with air, it can be used as part of a structural elements; thirdly the mass of water could work as a sound barrier so it can be used as sound insulation material . The following pages will focus on the second and the third use of water in architectural applications. The research investigates innovative applications of water in architecture and for this reason an empirical approach was required.In fact, at present time, water is considered nor a structural neither an insulation material for architecture. For this reasons standard computation software can not deal with it. Thus, the research was based on the tests of two mock-ups. The first prototype concerns a 200 mm thick panel filled with water. The second prototype is a “waterbeam” of 2 m span, starting from the Tensairity® technology principle.