This brochure presents the comparative advantage of UNEP and the catalytic role it plays when influencing other partners and UN agencies in meeting the global challenges of water. The paper highlights some of the achievements of the organization and a number of success stories over time and the contemporary challenges of the water so they can be considered along with partners as part of the international agenda. The cases presented illustrate the work of UNEP global, regional, national, basin and sub​​-basin. The topics covered include water quality, ecosystem restoration, management of climate change and disasters, the green economy and water governance.