This work reviewed a large and fragmented body of academic and grey literature on water resources in Lebanon. The objective was to assess and curate the existing knowledge base that reflected the importance of water-related concerns. Studies were classified into four topics: water balance, quality, management and governance, each of which was subdivided into sub-topics. Bibliometric analysis was performed, the content was summarised and discussed, and future directions were proposed. In terms of water balance, precipitation requires more research, as available rainfall maps are outdated. Despite an increase in the number of weather stations, their spatial distribution and data continuity remain problematic. Snow cover area and duration differed among studies; thus, it also requires more research. Estimates of evapotranspiration lack comprehensive coverage and often focus on specific crops. Surface-water studies are rare and have low temporal resolution. River flows have high temporal and spatial variability, emphasizing the importance of groundwater, which is overexploited. No consistent trends in climate change impacts were detected. More research is needed in all of the hydrological cycle components. On the other hand, water quality is degrading rapidly with microbiological pollution in most rivers. Groundwater degradation, saltwater intrusion, nitrate pollution, and pesticide contamination pose significant challenges. In addition, emerging pollutants are also being detected. In terms of water management and governance, Lebanon's water framework is complex, involving many laws, institutions, and international partnerships. Despite reforms, challenges remain. Water management has evolved from being state-centred to having increased involvement by international organisations and the private sector. Access to public water networks has improved but remains intermittent. Wastewater networks are expanding, but treatment capacity remains limited. Finally, this work made it possible to quantify the research work and projects carried out in each Lebanese basin, which made it possible to identify gaps in study topics and areas. We hope that this work contributes to the ongoing debate about water security and serves as a resource to support water security and solutions for researchers, educators and policy makers.