The narrative of technological conquest, modernisation and sanitary improvements has been influential in shaping the historiography of nineteenth-century water infrastructures. Although technological and scientific changes were important elements, however, the transition from the early modern system of water provision to an industrial one also involved resistance, conflict, and competition between different social groups. This article focuses on the issues of drinking water accessibility and related conflicts. It examines archival records of the daily water management, infrastructure projects, and municipal minutes of nineteenth-century Milan, Naples and Venice, as well as documents produced by local communities. Contrary to the consolidated narrative of decline and decay succeeded by innovation, the article contends that the early modern water infrastructure was complex, composed of many elements assembled into a whole, and that differences between these and modern water systems should be sought not in the assumed degree of systematicity. Instead, the division between the two types of systems was manifested in the latter type's scale and its driving concepts, derived from a view of the future for which modern water infrastructures were planned. Simultaneously, the creation of new social boundaries and the increase in inequalities in water access were among the products of modern infrastructure.