The agitated existing debate between traditional historiography and revisionist positions regarding the nature of the so-called “Visigothic” churches derives, fundamentally, from the proposal that a series of techniques and skills were lost during Late Antiquity. In this paper, I would like to add to the debate by introducing the results from my research on the evolution of aqueducts and water supply in the cities of post-Roman Iberia. The evident lack of proper maintenance and structural repairs fits within general patterns of late antique urban transformations such as the declining interest of curiales in public munificence and the crisis of the municipal institution. But added to this we must see a technical and technological disruption between the Roman past and the Visigothic centuries, which becomes evident when compared with the situation in the Umayyad period and parallels similar developments in other technical skills, such as pottery productions. In this context, the aqueduct of Reccopolis stands out as a unique example of brand new hydraulic infrastructure. Considering how unique the circumstances of Reccopolis are (i.e., royal foundation) and the links between the Visigothic monarchy and the Eastern Empire (where engineering skills were preserved), there is also a case to propose the eventual presence of Eastern engineers linked to this main construction project. Overall, I propose a model in which the lack of demand throughout the fifth and sixth centuries, together with the dismantling of the Imperial state apparatus and the disarticulation of the early Roman municipal system (which favored the construction of aqueducts in the first place) caused a fatal disruption in the transmission of engineering knowledge which, by the period of Visigothic state formation, could only be satisfied by tapping into the active networks of engineering training of the East.