The abundance of water and water infrastructure in the city of Rome not only provides for essential needs, but also serves as a cultural background for the urban life and pleasures of Rome’s citizens. Water plays an equally important role in the economic development of the Roman provinces. We have already described the development of the water wheel as it appeared in all of the Empire. But water management and exploitation went much further than this. Water had to be removed from the deepest galleries of mines, and massive quantities of water were needed to obtain lead, silver, and gold from their ores; the remnants of such ore-washing installations have been found in many of the provinces. In addition, the textile industry relied upon a steady supply of water. There is also of course agriculture, for which irrigation is required to support plentiful yields in southern and eastern regions. It is in these provinces, where water is less abundant and often scarce, that there is the most plentiful archaeological evidence of water acquisition and use. The most spectacular evidence is that of the Roman dams constructed in Spain, North Africa, and the Orient. Before describing these projects, as well as projects other than dams, let us first introduce Roman dam-construction technology.