<p>Water crises are a global risk, but the concept of water vulnerability remains fragmented. This systematic review identifies and compares the conceptual framings underpinning different research approaches, with attention to how human dimensions are represented under climate change. We reviewed 62 peer-reviewed articles published between (Li 2005) and 2024. Our findings show that water vulnerability scholarship remains strongly rooted in hydrological and environmental sciences. System-centred, top-down, and expert-led approaches dominate the field. Social science contributions, qualitative methods, and participatory or stakeholder-driven designs remain peripheral. Low-income and highly exposed regions, notably Sub-Saharan Africa, remain underrepresented. We synthesize the definitions of water vulnerability into four overlapping framings: water systems, water users, socio-ecological systems, and water infrastructure. We also argue that these framings can be understood as linked components of a natural-social system through which water resources, infrastructure, governance, and users jointly determine whether human water needs can be met. Across these approaches, five recurrent challenges limit the robustness and policy relevance of assessments: data shortages, scale mismatches, methodological oversimplification, subjective indicator choices, and unresolved uncertainty. The paper contributes by clarifying conceptual framings, showing the limited uptake of bottom-up approaches, and proposing a research agenda that connects long-range modelling with locally grounded assessment.</p>