In the early seventies, several high head drop structures were built as part of the construction of the Mexico City deep drainage system. The deep structures solved the problem of connecting the combined sewer system from street level to deep underground tunnels that enabled water discharges from urban areas. As it is common that the space available to build this type of structures is limited, the vertical drop may be several dozen meters, the discharges are extremely variable and it needs to function as sound- and vibration-free as possible; it is therefore necessary to carefully design, test in model and eventually build large drop shafts that take into account all of these conditions. Based on an Italian design (Drioli, 1947), a simpler drop shaft structure was proposed and tested in the late sixties for the Mexico City deep drainage system. It consisted of a spiral entrance that induces a strong vortical movement to achieve the adhesion of the water fall to the pipe walls for both small and large discharges. After more than 35 years of operation, the hydraulic behavior of this drop shaft has been satisfactory. As its characteristics and study results have never been published in English or in an international media, it was considered important to publish them and to highlight the advantages that this type of high head drop shaft has in terms of others found in specialized literature which can be more complicated and expensive.