Bioenergy is the production of renewable energy from organic material. It corresponds to three main feedstock categories (agriculture, forestry & waste) for three main uses (transport, heat & electricity). The development of bioenergy is often retained as a positive option due to its contribution to the mitigation of climate change, agricultural and rural development, energy security, innovation policies. Nevertheless, concerns have been raised during the last few years about risks or bad practices, sometimes evolving into large scale controversy, especially in relation to GHG emissions. The need to ensure that bioenergy development will be based on sustainable water management is essential, taking into account the need to increase food production and to accommodate simultaneously other uses of water resources, both for quantity & quality. This publication thus contains data and information related to methodologies of impact assessment, practical case studies, scenario analysis, discussion of sustainability certification schemes, all focusing on bioenergy & water. This publication has been prepared as a follow-up of the Session on Bioenergy & Water of the Sixth World Water Forum (Marseille, 2012). This document was prepared by the Joint Research Centre of the European Commission, with the support of the Twente University (Netherlands) and of the International Energy Agency Bioenergy Task 43 (Biomass Feedstock for Energy Markets). This Report is based on scientific contributions from Argentina, Australia, Brazil, the European Commission, France, Germany, India, the International Energy Agency, Netherlands, South Africa, Sweden and the United States. This document is aiming to be a useful reference for those interested in the sustainability of bioenergy and a contribution to the diffusion of good practices of water management at global, national or local level.