Water security faces escalating threats from both natural and anthropogenic pressures, including scarcity, pollution, climate change, disasters, and conflicts, with an increasing share of the global population—particularly in China—experiencing acute shortages. Rising population, economic development, and agricultural expansion intensify water demand, while untreated wastewater and agricultural pollutants exacerbate quality concerns, highlighting the intertwined challenges of water quantity and quality. To address these issues, this study provides a comprehensive review of current water security research. Our methodology involved a systematic synthesis of peer-reviewed literature, structured around four key themes: (1) assessment frameworks, (2) core indicators, (3) analytical methods, and (4) management strategies. This thematic analysis was designed to map the evolution of these tools, identify persistent research gaps, and inform pathways toward sustainable governance. The results, directly linked to our analytical framework, reveal a clear trend in assessment frameworks toward multidimensional, resilience-oriented approaches that integrate water quantity, quality, accessibility, ecological needs, and socioeconomic factors. Our review of analytical methods and indicators confirms the widespread application of tools such as DPSIR-based models, hierarchical systems like the Water Security Index, water footprint metrics, and hydrological models (e.g., SWAT, VIC) for evaluating water stress and supply-demand balances. However, our synthesis also highlights that these tools often struggle to capture complex causal dynamics, spatiotemporal variability, and critical water-society-ecology interconnections. Finally, the analysis of management strategies underscores the importance of combining technological, institutional, and governance measures—from traditional practices to adaptive urban management—to secure long-term water access under future pressures. Overall, by systematically mapping the applied tools and their limitations, this study underscores the need for holistic, context-sensitive, and forward-looking approaches to enhance water security at local, regional, and global scales.