Water-related disputes in India have been a fraught area of contestation between state governments in the post-colonial period. Since the late 20th century, much of this conflict has been centered on mechanisms of legal adjudication both through the centralized state machinery of tribunals set up by the central government and by legal suits brought by states before the Supreme Court. Formal records of tribunal and court judgments provide skeletal accounts of legal claims, technical evidence, and judiciary responses between unitary state governments with hardened positions and conflicting interests. Tamil Nadu, a lower riparian state is reliant on water-sharing arrangements and the shared management of water-related infrastructure with its three neighboring states of Andhra Pradesh, Karnataka, and Kerala. The water-related agreements that link Tamil Nadu with its neighbors vary in significant ways in terms of the scope of the agreements, the kinds of issues under contention, the political dynamics of the agreement, and the outcome and implementation of each of the agreements. Political, institutional, and agential dimensions of state action are both shaped and constrained by historical structures of political economy. Both centralized structures of the colonial state and the political economy of India’s planned developmental state shape this set of interstate water negotiations and disputes that weigh on the states that share water resources and infrastructure in Southern India. While historical processes have produced the structural conditions that have shaped such disputes, recent policies of liberalization have intensified conflicts over water. For instance, processes of urbanization and city-centric models of growth have increased pressures on water resources in India. Social scientific scholarship that has focused on the politics of economic reforms and on the ways in which reforms have been shaped by India’s federal structure has tended to treat states as discrete entities. Such scholarship has analyzed the impact of India’s federal structure on reforms through a focus on relationships between states and the central government. While this has produced a heightened focus on the significance of federalism in the post-liberalization period, such work has paid less attention to relationships between states. The focus of such social scientific scholarship on particular sectors of the economy (such as telecom, electricity, and land/real estate) that are visibly associated with reform policies has compounded this analytical gap. Unlike such sectors, water is not contained within the territorial boundaries of states. A historical perspective on water disputes provides a means for unsettling the conventional analytical boundaries of political scientific conceptions of federalism in the post-liberalization period.