WaterTOP is a COST Action, i.e. a pan-European network on “Taste and Odor in early diagnosis of source and drinking Water Problems”. WaterTOP is funded by COST (2019-2023). Brief description of waterTOP: Unpleasant taste and odor (T&O) of water can indicate quality problems or possible risks for human health and can make water unacceptable by consumers. A plethora of water T&O of natural or anthropogenic origin can enter water at the source, during water treatment or in distribution networks. Resolution of water T&O problems requires integration of a) sensory analysis to describe the problem, b) chemical analysis to determine the identity and concentration of T&O c) assessment of associated risks and d) suitable water treatment to control T&O. Expertise in Europe across those dimensions are yet scattered and fragmented. The main aim of waterTOP is to increase capabilities and capacities in Europe for solving water T&O, by creating the first European network of multi-disciplinary experts, end-users and stakeholders in the field. An “innovation by integration” approach is adopted, incorporating novel cross-sector knowledge transfer from the food sector, new international collaborations, vertical “source to tap” risk assessment strategies and horizontal integration with overlapping sectors, i.e. aquaculture, manufacturers of materials in contact with water, sensors and analytical technologies. WaterTOP will have strong impact in improving protection of public health and water resources, quality of life, use of tap water, consumer’s awareness and involvement in water quality issues and professional development of young researchers in the field. It will largely contribute to the implementation of the new (recast) EU Drinking Water Directive and to the development of European leadership in the science and technology of water quality.