Water supply and water management in Antiquity represent more than Modern World can imagine about how people in that period used to think about, and exploit the resources they had, aiming at developing and improving their society and own lives. This paper points out examples of how they handled different situations, and how they managed to cope with the growing number of population in the urban areas, by adapting or by improving their water supply systems. The paper tries to emphasize the engineering contribution of Rome and the Roman Empire, mainly in the capital but also in the provinces, as for instance the today territory of France, by analysing some aqueducts from the point of view of modern Hydraulic Engineering. A third order polynomial regression is proposed to compute the water flow rate, based on the flow cross-sectional area measured in quinaria . This paper also emphasizes on contradictory things between what we thought we knew about Ancient Roman civilization, and what could really be proven, either by a modern engineering approach, a documentary approach, or by commonsense, where none of the above could be used. It is certain that the world we live in is the heritage of the Greco-Roman culture and therefore, we are due to acknowledge their contribution, especially taking into account the lack of knowledge of that time, and the poor resources they had.