Despite its temperate, humid sea climate, Belgium is a European country experiencing water shortage (overextraction of groundwater) and using almost 100% of its renewable water resources. Water reuse is not only favoured by the existing legislation, but is also estimated to be a cost-effective solution for industrial and indirect potable purposes (Thoeye et
al., 2000). In Wulpen WWTP, over 2.5 million m3/year of urban effluent will be treated by microfiltration (MF) and reverse osmosis (RO), stored for 1–2 months in the aquifer and used for water supply augmentation. Another project, under investigation in Heist, will evaluate both MF/RO and MBR technology, to treat 10,000–24,000 m3/d and recharge the aquifer.