This handbook on adaptation of urban water systems to climate change is an initiative of the SWITCH project and the result of collaboration between ICLEI – Local Governments for Sustainability, the International Water Association (IWA) and the UNESCO-IHE Institute for Water Education. It draws on the research and findings from the SWITCH and PREPARED EU Framework Programme projects. This handbook is a “living” document that is envisaged to be updated yearly with new information and experiences and is complemented by a website with additional information (www.adaptationhandbook.org).