Preventing groundwater contamination and protecting its quality against harmful impacts of global and climate change The European Union has made noticeable progress in terms of reducing concentrations of nutrients in groundwater and in rivers through the implementation of dedicated policy measures. However, Member States identified that diffuse pollution is still a significant pressure that affects 35% of the area of groundwater bodies[[European Environment Agency The European environment — state and outlook 2020 https://www.eea.europa.eu/soer-2020/intro]], while quality standards (pesticides, herbicides, etc.) were exceeded in 15% of the groundwater bodies studied. Climate change and increasing water demand will exert significant pressures on groundwater quality, notably where the combined effect of reduced hydrological flows, water table depletion and sea level rise endanger the integrity of coastal aquifers and groundwater quality due to saline water intrusion. Extreme events like higher tides, storm surges and inland flooding events, and consequent pollutant and pathogen runoff, will put at risk wetlands and reservoirs, estuaries and ecosystems, jeopardising an efficient and qualitatively good groundwater recharge. Rising water tables in urban and rural areas, caused by e.g. higher sea level, changing water use or variable precipitation patterns, could potentially affect pollution sources (sewage, runoff infiltration, dilution of soil pollutants, salinization, etc.) and deteriorate the quality of groundwater.Additional knowledge is needed to understand the synergistic effects and risks of multiple stressors and pollutants on groundwater quality to better evaluate the impacts of global and climate change, particularly in highly vulnerable areas affected by diffuse pollution, anthropogenic activities and/or water table fluctuations. Actions in this field should aim to identify and assess sources and pathways of groundwater pollution to inform risk management plans at basin/regional scales, with particular consideration of aquifer recharge with reclaimed water and persistent pollutants.Further developments are expected in terms of cost-efficient monitoring strategies, which could include new tracers and sensors, increased sampling and analytical capacity, as well as integrating IT advances and geophysical modelling.Proposals in this area should assess possible options and anticipate novel strategies to protect groundwater quality by considering the harmful effects of and threats from climate change. Actions in this field should focus on preventive measures and consider technological and non-technological solutions, and should engage with policy and decision-making bodies.In general, the participation of academia, research organisations, utilities, industry and regulators is strongly advised, as well as civil society engagement whenever necessary, also aiming to broaden the dissemination and exploitation routes and to better assess the innovation potential of developed solutions and strategies.If appropriate, applicants are advised to seek complementarities and synergies, while avoiding duplication and overlap, with relevant actions funded under Horizon 2020 calls[[Including access and use of data and information collected through long-term environmental monitoring activities supported by national and/or European research infrastructures.]], as well as targeted topics supported in the last Horizon 2020 and Horizon Europe calls, addressing micro/nano-plastics, persistent and mobile pollutants, such as per- and polyfluoroalkyl substances (PFAS), pharmaceuticals and contaminants of emerging concerns (CECs), pathogens and antimicrobial resistance.In order to better address some or all of the expected outcomes, international cooperation is strongly encouraged.In this topic the integration of the gender dimension (sex and gender analysis) in research and innovation content is not a mandatory requirement.