The Sanitary Engineering Laboratory (www.eyt.gr) of the National Technical University of Athens (www.ntua.gr) together with the Hellenic Water Association (www.hwa.gr) are delighted to host the 13^th IWA Specialized Conference on Small Water and Wastewater Systems (SWWS) together with the 5^th IWA Specialized Conference on Resources-Oriented Sanitation (ROS). The event is a continuation of the previous successful Conferences of the 10^th SWWS and 3^rd ROS (Venice, Italy), the 11^th SWWS (Harbin, China) and the 12^th SWWS and 4^th ROS (Muscat, Oman). The Conference, which will take place in Athens, Greece, will bring together researchers, engineers, water practitioners from academia, industry, water utilities, public authorities and administration to exchange know how and experiences. Within the Conference knowledge and expertise will be disseminated on innovative systems, technologies and processes which are/can be applied at small and decentralized regions for the management of water and wastewater. The whole water supply chain is considered from water abstraction to treated wastewater disposal and reuse. Furthermore, resource oriented sanitation as a route to sustainable and ecologically sound sanitation will be discussed focusing on developing countries.