Advanced water treatment can be done by sand filtration, active carbon filtration, microretention with or without ultrafiltration membranes. The addition of these stages leads to significant improvement in water quality by removing suspended micropollutants from previous treatment stages or even untreated water. It is particularly helpful when there are strict limits to be achieved for certain pollutants or before other water treatment processes. It is a fast, efficient and economical solution to obtain an effluent free of suspended solids and to remove oxygen-consuming substances. Carbon filtration can be used before ozonation.