The fourth edition of the United Nations World Water Development Report (UN WWDR), ‘Managing Water under Uncertainty and Risk’ is a comprehensive review of the world’s freshwater resources and seeks to demonstrate, among other messages, that water underpins all aspects of development, and that a coordinated approach to managing and allocating water is critical. The Report underlines that in order to meet multiple goals water needs to be an intrinsic element in decision-making across the whole development spectrum. It was launched at the 6th World Water Forum in Marseille by Irina Bokova, UNESCO Director General, and Michel Jarraud, UN-Water Chair. About UN WWDR4 :The UN WWDR4 aims to encourage all stakeholders both in and out of the ‘water box water managers, leaders in government, civil society and businesses to engage early in decision making processes to improve the quality and acceptance of decisions and the probability of successful implementation. It highlights that more responsible action by all water users has enormous potential to lead to better outcomes but requires political, social, economic and technical responses at all levels of government, businesses and communities, from local to international. What’s new In the UN World Water Development Report (WWDR) series, the UN WWDR4 represents a milestone. While providing a comprehensive assessment of the world’s water resources it also introduces a strong thematic element. Building on the UN WWDR3 in the recognition of the externalities, the UN WWDR4 elaborates on the interactions between water and the drivers of change. The UN WWDR4 describes the major changes, uncertainties, and risks taking place in the world and their links to water resources. It gives account of the status and the trends related to water supplies, uses, management, institutions and financing; highlights regional hotspots, and addresses issues such as gender equality, water-related disasters, health and the role of ecosystems.