H2OSEG is a research project funded by the BBVA Foundation as part of the Prismas y Problemas Programme. Its main objective is to define and explain the risks that could compromise water security in Spain, both for society and aquatic ecosystems, and to propose integrated solutions to ensure sustainable, fair and equitable water use. The H2OSEG project is coordinated by the Catalan Institute for Water Research (ICRA) and involves researchers from the Andalusian Institute of Marine Sciences-CSIC, the Institute of Environmental Diagnosis and Water Studies-CSIC, the Arid Zones Experimental Station-CSIC, the University of the Basque Country-Euskal Herriko Unibertsitatea, the IMDEA Water Institute, the University of Barcelona, the University of Cantabria, the University of Lleida, the University of Extremadura, the University of the Balearic Islands, the Rovira i Virgili University, and the University of Valencia.