A comparison of the hydraulic equipment of urban sites in south-eastern Roman Hispania (Betica and Tarracona) and Caesarian Mauritania has never been carried out before. The aim is to examine the types of water supply, storage and distribution structures of thirteen coastal sites located on the two shores of the Mediterranean, trying to identify their particularities and their common points in order to draw up an initial assessment. This perspective is interesting because this study area has the advantage of involving cities with relatively similar climatic contexts (high heat, irregular rainfall) and similar topography, as they are located in coastal areas in the west of the Mediterranean basin. We can see, for example, that the majority of the cities in the corpus are supplied by at least one aqueduct. Moreover, in both territories considered, there is a significant number of large water storage structures (reservoirs and rainwater tanks) and the majority of the sites had thermal baths. Logically enough, the provincial capital of Caesarian Mauretania has a large number of hydraulic structures. This research deserves to be widened in the future, and this first assessment demonstrates the potential of such a study.