December 2008 marked the completion of Stage 2B of the Western Corridor Recycled Water (WCRW) Project in South East Queensland, Australia. With a maximum combined production capacity of 232 million litres of purified recycled water a day, it is the third largest recycled water scheme in the world and the largest in southern hemisphere. A seven-barrier approach has been used to ensure very highest quality, safe water is produced at all times for the purpose of indirect potable reuse. Three of these barriers occur in the advanced water treatment section of the WCRW Project: micro- or ultra-filtration (MF), reverse osmosis (RO), and H(2)O(2)/UV advanced oxidation. In addition to providing very efficient disinfection, the advanced oxidation process specifically aims at destroying compounds not fully rejected by RO that are potential health hazards. This includes N-nitrosodimethylamine (NDMA), which is a potential carcinogenic product likely to be formed by chlorination or chloramination of wastewaters. As in many other countries, Australia has adopted a stringent guideline limit for this compound of 10 ng/L in purified recycled water. After 16 months of operations of the WCRW Project's first plant, the advanced oxidation system has been proven effective in removing NDMA and ensuring 100% compliance with the regulation at a controlled cost.