Wastewater and drinking water treatment are essential elements of urban infrastructure. In the course of the last century there has been enormous technical development, so successful that for the general public in industrialized countries this infrastructure is hardly noticed. Nevertheless there is ongoing activity to further improve the existing processes. The IWA Leading Edge Technology conference held in Prague helped to stimulate this development and this book helps disseminate the results. A selection of presentations from the conference are included in this volume. Wastewater and drinking-water treatment are normally considered as two separate fields due to the very different boundary conditions that apply. Nevertheless several issues such as membrane processes, removal of micropollutants and water reuse are of crucial importance to both. This potential for cross-fertilization further enhances the value of this collection of high-quality articles that delineate the leading edge of research and development in water and wastewater treatment.