Cities face substantial water governance challenges, even more so when their activities are water-intensive, as global tourism is. As the lower-most level of government, municipalities face important challenges when dealing with water stress. Designing robust urban water policy thus may require us to challenge currently popular modes of governance by river basin councils, as predicated by the integrated water resources management (IWRM) paradigm. In this paper, I conduct a public policy analysis of a case study of intra-urban water conflict in the Mexican city of San Miguel de Allende (SMA), an extremely popular tourist destination with substantive water scarcity challenges. I draw insights from an application of the Institutional Grammar Tool, IGT (as proposed by Ostrom and Crawford) on a series of textual datasets derived from ethnographic, qualitative longitudinal field research, document analysis, and elite interviews with stakeholders to explain the reasons underlying community concerns about urban water supply which have derived in conflict in San Miguel de Allende and increasingly manifested over the past few years (2017–2020). My analysis suggests that to tackle growing intra-urban antagonism derived from increasing water insecurity in San Miguel de Allende, a more localized, micro-watershed approach might be more fruitful than a traditional river basin council strategy.