Berliner Wasserbetriebe has started a pilot project about new sanitation concepts in conjunction with Vivendi Water in the framework of the Kompetenzzentrum Wasser Berlin. In order to define the experiments for testing new, sustainable sanitation con-cepts a pre-study has been done. This study includes a cost comparison between two new sanitation concepts with gravity and vacuum separation toilets and the conven-tional system. It could be demonstrated that the new sanitation concepts may have cost advantages depending on the situation. This was a further motivation starting a pilot project in Berlin/Brandenburg testing the above mentioned toilet systems under realistic conditions. The operation of the gravity separation toilets concept will start in the summer 2003.