Blind spots in global water quality monitoring

Abstract Poor water quality threatens human and environmental health, as well as the usability of water for sectoral purposes. Despite widespread recognition of its importance, our knowledge of water quality is severely impaired by a lack of information. However, global water quality data is required to assess the critical regions (hotspots) where pollution poses risks to safe water use, economic development and ecosystem services and health. Here, we identify blind spots in current water quality monitoring efforts, elucidating on the associated challenges for diagnosing water quality issues and the knock-on effect for both science and society. Furthermore, we provide recommendations for addressing these blind spots – on which strong emphasis is placed on improved accessibility and transparency of existing data in addition to increasing global water quality monitoring efforts.