The aquifer vulnerability front to non-point contamination, as it is the reuse of wastewaters and sludge in agriculture, can mainly be very high if the characteristics of the vadose zone are not the suitable. This is carried out that the polluting compounds of these waters and sludges do not undergo processes that give rise to a diminution of their presence. An example of the polluting effect by reuse of wastewaters in irrigation in the Valley of Leon aquifer (Mexico) is presented. It has studied the deterioration of the groundwater quality by presence of some of the polluting agents, that are present in the wastewater. In other cases, the vadose zone act as barrier a contamination originated, for example, by the application of the sludge in agriculture. This fact has been able to verify in an experimental site, located in the Valley of Toluca aquifer (Mexico), where the behavior of nitrogen and phosphorus has studied.