​Water security remains a challenge for over 75% of the countries in Asia and the Pacific, where poor sanitation and wastewater management leads to the contamination of fresh water sources and is a major cause of disease and death, while also impacting eco-system health. In 2012, nearly 180 million people lacked access to improved sanitation in South-East Asia alone. Water is a resource with competing uses and interlinkages with the ecological, social and economic systems, and thus needs to be managed through a comprehensive approach. Enhancing knowledge-sharing and cooperation in Integrated Water Resources Management (IWRM) in Asia and the Pacific was unanimously accepted by all member States at 69th Session of the UN ESCAP in 2013, Resolution 69/8. IWRM is a key strategy for an efficient, equitable and sustainable development approach. Through IWRM, water is treated as an economic, social and environmental good, ensuring that policies and options that guide water resources management are further analyzed within integrated frameworks of Water and Green Economy and Water and Green Growth. Decentralized Wastewater Treatment Systems (DEWATS) refer to a technical approach, enabled by the respective norms and institutional support, which takes into consideration local economic and social situations, and was developed for integration in comprehensive wastewater strategies, following IWRM principles. More