Despite strong interest and conflict research spanning multiple disciplines, connections between water flows and conflicts remain unclear, due to incomplete datasets on water-related conflict-cooperation events and poor understanding of socioeconomic and biophysical causes of such conflicts. The dataset on water-related conflict-cooperation events compiled in this study extends to 2019, updating previous datasets that covered only up to 2008, yielding important new insights on cooperation-conflict trends. Global and regional trends were analyzed using the new events dataset, together with changes in hydroclimatic variables and population density. The analysis revealed that water-related cooperation was far more common than conflicts across all regions, in both drier and wetter climates, indicating that abundance and lack of water can both promote cooperation. However, conflict events were more common in drier climates where water is scarcer. This cooperation-conflict balance shifted in the 2000s, with conflict events increasing, to outnumber cooperation events in 2017. The main shift occurred in Africa and Asia, where increased conflicts in Africa coincided with a prolonged period of below-average precipitation and severe drought, while the shift in Asia coincided with increased evapotranspiration caused by human activities and increased population density. Differences between regions were confirmed by event descriptions, with events in Africa relating to water access and farmer-herder conflicts, and events in Asia relating to irrigation and dam construction. These differences highlight the need for regional-scale analysis of water-related conflict-cooperation trends and pathways. With climate change and human activities expected to increase, the increasing trend in conflict events could persist, with water resources becoming a more frequent cause of future conflict. Identifying these complex cooperation-conflict changes is vital in determining future actions required to reduce conflict events and promote cooperation on water.