Pretreatment before reverse osmosis systems in water reuse plants is necessary to prevent rapid fouling. The secondary effluent can at times contain a high suspended solids load with a high proportion of colloidal material, organic compounds and bacteria. Such constituents can cause irreversible fouling of downstream RO systems if not successfully removed during pretreatment. To minimise RO membrane organic fouling, a pretreatment combination including advanced oxidation (ozonation), ceramic MF and biological activated carbon (BAC) was assessed. It was found that fouling formed by the feed wastewater pretreated by the combination of ozonation + ceramic MF and BAC can be easily removed by deionised water flushing, in comparison with MF, BAC, or ozone + MF.