Securing drinking water quality by protecting water sources against pollution, providing innovative monitoring and treatment solutions and ensuring safe distribution The European Union policy framework has secured public safety and health objectives by the Drinking Water, Bathing Water and Floods Directives (EU, 1998, 2006, 2007), and the ongoing development and implementation of minimum requirements for water reuse. Despite the valuable output of implemented measures, some persistent problems are still a major, and sometimes unknown, risk factor for human and ecosystem health. Past contaminated sites and industrial activities managing hazardous chemicals, such as highly persistent compounds, together with agriculture and food production (pesticides, herbicides, antibiotics etc.), and household activities release a number of substances that individually or combined represent a concern for the safety of drinking water supplies. Detrimental effects of natural/human-made disasters and increasing water temperatures due to climate change could deteriorate the quality of drinking water sources by favouring the conditions for enhanced eutrophication leading to algal and cyanobacterial outbreaks as well as pathogen development or the spread of invasive species. Emerging concerns are also rising at the level of drinking water treatment and distribution, notably in relation to disinfection operations, materials and products, ageing infrastructure, biofilm growth and possible harmful effects of unintentionally formed by-products and metabolites.Actions in this field should aim to expand the knowledge base required to identify, assess and prevent pollution threats (micro-pollutants, pathogens, toxins, algal blooms, etc.) and the combined effects of multiple stressors on water sources, including risk assessment and management, to protect drinking water preparation and distribution. Particular attention to extreme weather events and possible synergistic effects affecting hydraulic flows, temperatures and pollutants’ loads should be considered, whenever appropriate.Advanced water quality assessment needs further development of sensors sensitivity, automated routine monitoring and fast analytical responses that fully integrate IT advances. Proposals in this topic should aim to extend the current analytical capacity to enable among other issues the detection of suspect and non-targeted pollutants, resulting in robust and reliable monitoring systems for consideration in future legislation. They should also consider the requirements of the revised Drinking Water Directive as regards catchment management.Unintended disinfection by-products (DBP) and interactions with chemical reagents used for drinking water treatment (DWT), engineering and contact materials as well as the combined effects of biofilms formation are emerging as hazardous chemical risks that could affect human health. Proposals in this field should further extend the knowledge base of mechanisms and reactions leading to DBP formation by analysing raw water quality and precursors, as well assessing DWT operational parameters, including disinfection needs, methods and doses. Advanced DWT solutions should explore integrated systems coupling different treatment technologies and strategies enabling the optimization of the operational DWT effectiveness while removing DBP risks.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. Whenever possible, proposals should consider already developed digital solutions for real-time water monitoring systems. Activities related to water reclamation and reuse, indirect potable use or alternative water sources are beyond the scope of this topic.In order to better address some or all of the expected outcomes, international cooperation is encouraged.In this topic the integration of the gender dimension (sex and gender analysis) in research and innovation content is not a mandatory requirement.