The World Health Organization estimates that globally one billion people are without access to safe water and two billion people without adequate sanitation. The health consequence of such a situation is very serious and demands urgent appropriate action. The centralised system, which is still promoted all over the world, will not help in providing water and sanitation for all as it depends on huge financial and technological resources that are often not available. The International Conference on Decentralised Water and Wastewater Systems held in Fremantle, Western Australia in July 2006 (organised by the Environmental Technology Centre at Murdoch University) promoted decentralised systems as a means of solving this problem. All the papers submitted at the conference underwent a review process. This book brings together a selection of papers presented at the conference. The papers selected for inclusion in WEMS 13: Decentralised Water and Wastewater Systems promote the concept of decentralised systems, focusing on the design, operation, maintenance and management of small water and wastewater treatment plants and the uptake of decentralized systems. This book will be a valuable resource to industry practitioners, consultants and academics.