This article explores the reliance of watermen (acquaroli) in early modern Venice on increasingly sophisticated waterwheels, designed, produced, and patented by competing inventors during the sixteenth and early seventeenth centuries, to load fresh water supplies that supplemented the rainwater on which the city otherwise depended for its freshwater needs. Using a range of archival and printed sources, this article examines the tools that delivered water to the watermen's barges and the state-sponsored competition this spurred among inventors. More broadly, the article investigates how Venice's patent process compared to those elsewhere in sixteenth-century Europe, with specific attention to the status of petitioners, contemporary notions of expertise, knowledge flows, and the role of the state.