Mexico faces severe water scarcity due to population growth, industrial activities, and climate change. The arid and semidesert conditions prevalent in northern Mexico, particularly in Nuevo Leon, significantly accentuate the challenges associated with water scarcity. This region is vulnerable to water scarcity due to minimal rainfall, recurrent droughts, and the increasing pressure of water demand from the densely populated Monterrey. We examined the disparities that contribute to water poverty by comparing water scarcity between rural and urban populations in Nuevo Leon. The results revealed significant contrasts in water scarcity between the two populations, indicating that different factors contribute to water poverty based on regional, territorial, and cultural characteristics. We selected the water poverty index (WPI) as an evaluation metric due to its inherent compatibility with available data sources, which facilitates its application to stakeholders and ensures comparability with other regions. This study contributes to studies on water scarcity assessment by addressing a critical limitation of the WPI. We compared three weighting methods—equal weight, principal component analysis (PCA), and analytic hierarchy process (AHP)—and identified that PCA and AHP demonstrated a superior performance compared to the standard methodology. These findings underscore the importance of considering region-specific conditions, as well as socioeconomic disparities between rural and urban populations and their role in vulnerability to water scarcity in calculating water poverty. These insights provide valuable information for customized solutions to regional challenges, representing leading actions toward sustainable development.