The interest in ultra-(UF) and microfiltration (MF) membranes increases worldwide due to the extremely high water quality for the production of potable water in respect to particle retention, hygiene aspects and microbiological safety. Furthermore, the retention of dissolved and dispersed organic and/or inorganic water contaminants with membrane processes for the (direct) treatment of surface waters has recently become more important as documented by a growing number of installations, research projects and pilot plant trials. Actually, IWW and NGK are conducting laboratory and pilot plant experiments where water from the Ruhr River is treated by the hybrid process of coagulation/ MF. The aim was to evaluate the performance of ceramic MF and to optimise its process and operating conditions reflecting the actual needs and requirement of waterworks in Gen-nany. This contribution to the MDIW 2004 presents the actual experiences for the first month of operation with ceramic MF membranes from laboratory investigations and pilot plant experiments. The conclusions drawn were embedded into the future operation of the pilot plant.