Water and energy are two of the most important resources of the 21st century. Cities are one place where this water-energy nexus will become critical in the near future due to demographic movements, economic growth and an inexorable increase in demand. According to the UN, 54% of the world’s population lived in urban areas in 2014, a proportion that is expected to increase to 66% by 2050. European hydrological planning policies have traditionally been based on increasing the availability of water resources and the capacity to regulate them. In the case of the urban water cycle, these approaches have led to a gradual depletion of the resource (overexploited aquifers), reduced water quality, deterioration of aquatic ecosystems and conflicts between users with competing interests. In recent years, water and sewage treatment operators across Europe have been forced to use more energy intensive processes as a consequence of expanding water quality legislation. LIFE NEXUS will show the potential of micro-hydropower systems to recover the untapped energy deriving from abundant pressure (water head) or kinetic energy (water flow) in existing water networks in cities. The project will install micro-hydropower technology (energy generation and energy management) and test it for 15 months at the Porma drinking water treatment plant in the city of León (Spain). It will also develop the first European inventory of micro-hydropower potential in urban water cycles and assess the technical and economic feasibility of using the technology in potential locations. LIFE NEXUS involves some 40 stakeholders from Belgium, Ireland, Lithuania, Netherlands, Poland, Spain and the UK. The project targets the thematic priority for water and is in line with other EU energy- and water-related policies. By engaging a significant number of entities and policymakers it will have an impact on policy implementation and development. Expected results: Generation of 215 MWh/yr of renewable electricity, harvested from the energy currently dissipated by a pressure reduction valve located at the entrance of a drinking water treatment plant; The micro-hydropower installation will meet all of the energy needs of the treatment plant, leading to a 100% reduction in greenhouse gas emissions, based on an assumption of 140 t CO2equiv. per year of operation; Reduction of water leakages in the treatment plant by 0.5%, or more than 42 000 m3/yr, as a consequence of improved pressure control at the entrance pipeline; Assessment of the quantitative energy recovery potential along urban water cycles in European cities. The minimum micro-hydropower plant capacity with a payback time of less than 10 years will be determined for the different countries; Successfully demonstrating the technical and economic feasibility of micro-hydropower will allow authorities to increase the competitiveness and improve the sustainability of urban water provision.