Aqua Designer is a software tool for the design of the several processes of a wastewater treatment plant, from mechanical treatment via biology up to sludge treatment. Regarding the basis of calculation, the process and the construction all common process variations are to choice. Planning is supported by many auxiliary functions. As result Aqua Designer supplies extensive documents ready to be printed for official documents, including buildings, machines, operating costs and true scaled drawings. Aqua Designer is used world-wide for the planning of treatment plants.