Converting the inner city harbour Zollhafen in Mainz (Upper Rhine) into a new living district promotes a compact european city model by contributing to a decrease in land consumption and thus run-off. As a development outside of the municipal flood defense, it demands for flood adapted construction and a "retention-neutral" development to comply with German water legislation. The Zollhafen is being developed as a model project for flood adapted building in a partnership between the Stadtwerke Mainz Corporation (the municipal utilities company) as the owner of the harbour and the Ministry for the Environment of the State of Rheinland-Pfalz. Apart from defining requirements for building in the flood plain, different strategies and instruments are being developed to trigger innovative adaptive designs and to create public spaces which raise awareness for the inherent, but, due to the height of the site, rare flood risk.