During most water treatment processes, spent filter backwash water (SFBW) is generated. Reuse of SFBW is of concern because of the possible recycling of heavy metals, precursors for disinfection by-products and microorganisms. Innovations in membrane technology, especially in micro- and ultrafiltration processes, offer a suitable treatment for SFBW in order to guarantee a water quality necessary for reuse. Results from apilot-scale ultrafiltration plant with submerged membranes are presented. Experiments were performed with SFBW from a full-scale water treatment plant. The plant was operated with high fluxes of more than 40 L/(m(2.)h) using clarified and non-clarified SFBW. Best membrane performance was obtained using non-clarified SFBW. As a result, no space- and time-consuming sedimentation processes are necessary. The presence of powdered activated carbon in the SFBW did not have a negative impact on flux and TMP. Results confirmed that the filtrate can be used as an additional and safe water source. When a continuous maintenance disinfection was provided, filtrate was free of microbial contamination and could be reused without any safety concerns.