The urban space of colonial Rio de Janeiro was to a large degree structured by a water supply system drawn from European models, including aqueducts, fountains, and a network of underground pipes. This infrastructure, however, worked hand in hand with innumerable slaves responsible for the distribution of water from the fountains to individual households. The article analyzes the continuous social negotiation between white elites and Afro-Brazilian slaves regarding the localization, construction, usage, and valorization of the water works and the spaces produced by them. While the elites possessed the power, means, and traditions to design the infrastructure in the first instance, the slaves gave life to it, defined their eventual application and appearance, and more than once caused the white elites modify the works. Thus, by studying the city’s water supply, the article brings to the forefront the slaves’ ability to actively participate in the configuration of the physical and cultural identity of a colonial city.