Current scholarship on poverty in the U.S. borderlands argues that limited low-income housing and unenforced land development regulations cause poor domestic water access in south Texas's predominantly Mexican-American rural and periurban low-income communities (colonias). In this article, I argue that water politics, not only poverty or failed public policy, determined the trajectory of inadequate water access. Drawing from legislative archives, legal documents, and court records, I examine two companion legal cases (Jimenez v. Hidalgo WCID 2 et al. [1971] and Fonseca v. Hidalgo WCID 2 et al. [1971]) that challenged the ability of farmer-controlled water control and improvement districts (WCIDs) to dominate regional water governance by excluding colonias from district territory. This territorial exclusion denied colonias residents the right to vote for WCID board candidates and, thus, denied residents the political standing to change the district's operation from irrigation to domestic water supply. Drawing on current scholarship in critical legal geography, the article details how emerging legal discourses rescripted narratives about colonias residents’ access to water through debates over the political territoriality of the WCIDs. Moreover, the legal process shifted the terms of debate from voting rights to historical precedent, the market, policy failure, and prospective water rights. The final legal ruling against colonias residents foreclosed any standing they had in regional water governance and shunted them into their current position of passive consumers of dysfunctional public services with limited ability to change their relationship to regional water management institutions.