The membrane bioreactor (MBR) is based on the combination of a suspended biomass reactor and a separation step on porous membrane filtration. It presents several advantages in terms of water resource protection because of the great quality of the treated water that can be reused as well for irrigation, cleaning or cooling water on industrial site, domestic purposes (e.g. toilet flushing). The quality of the water, notably the absence of solids in suspension and turbidity, allows considering the MBR as a perfect tool for pre-treatment before desalination or preparation of water of very high quality. Moreover, because of its modular property, the MBR may also be favourable for developing a new wastewater network configuration in an urban area.