Since the 19th century, cities have been characterized as dynamic organic or inorganic systems that cycle a variety of flows (energy, water, materials, information, and humans) at increasingly rapid rates. In this presentation, I examine the significance of one urban flow – water – to the modern American city. Water is a particularly important element in the urban landscape because it relates humans to nature through technical networks, revealing fundamental political and social connections that are created when a natural resource is shared among urban populations. This presentation draws from theory and case studies in the disciplines of planning, architecture, geography, urban ecology, and science & technology studies to understand the contested nature of water in urban contexts.