The new treatment plant for the water of the Wahnbach-Reservoir with a capacity of 4,800 m^3/h (30,4 mgd) serves the city and region of Bonn. It will be in operation with full capacity in early 2002. The treatment process is based on flocculation and direct filtration but achieves outstanding performance and reliability from in house developed and refined new technologies, sophisticated layout and control strategies. The main goal is outstanding water quality with minimized treatment additives and residuals. Important features of the treatment include: destabilization of particles by ultra flash mixing of flocculant; ultrasound inactivation of motile plankton, that causes penetration of micro-organisms into the filtrate; compact, collision and shear optimized flocculation; high performance dual media direct filtration; water saving build up backwash technology; and, disinfection with DVGW-W294 challenge tested UV-systems. The concept was developed in-house and reflects 40 years of research and experience at the Wahnbach Reservoir Association. Includes 13 references, figures.