<p>Urban water security represents a major planning challenge in cities exposed to rapid environmental change, socioeconomic inequality, and institutional fragility, particularly in developing regions. In Maceió, Alagoas State (AL), northeastern Brazil, a large-scale urban mining disaster associated with decades of underground salt extraction has caused severe geotechnical instability since 2018, resulting in widespread infrastructural damage and the forced displacement of more than 55,000 residents. These transformations have profoundly affected urban space, public services, and hydrosocial dynamics, especially regarding water security. This study assessed intra-urban water security dynamics by comparing pre-disaster (2010) and post-disaster (2022) conditions through the development of a spatiotemporal GIS-based multicriteria model to support urban planning and resource allocation. Sixty-seven indicators were initially identified through literature review and official datasets and subsequently consolidated into twenty-six criteria through Exploratory Factor Analysis (EFA) and conceptual screening procedures. The criteria were organized into four dimensions: human, economic, ecosystemic, and resilience. The proposed framework integrates GIS spatial modelling and the FITradeoff multicriteria sorting method to evaluate spatial inequalities and vulnerability patterns across neighborhoods. Results revealed a substantial deterioration in urban water security between 2010 and 2022, with a 47% increase in neighborhoods classified under more vulnerable conditions. The most critical declines occurred in areas affected by population displacement and geotechnical hazards, reflecting cumulative pressures on infrastructure, service accessibility, environmental quality, and governance. The findings provide actionable insights for adaptive urban governance and disaster-risk-informed planning in vulnerable urban contexts.</p>