The Berlin Centre of Competence for Water (Kompetenzzentrum Wasser Berlin) together with its partners Berliner Wasserbetriebe and Veolia Water has started a demonstration project about new sanitation concepts. In order to define the experiments for testing new, sustainable sanitation concepts a pre-study has been performed. This study included a cost comparison between two new sanita-tion concepts with gravity and vacuum separation toilets and the conventional sys-tem. It could be demonstrated that the new sanitation concepts may have cost advantages depending on the situation. This was a further motivation to start a Demonstration project near Berlin testing the innovative toilet systems under realis-tic conditions. Operation of the gravity separation toilet concept started in October 2003.