In the development of technical studies in whichvariables related with information geographical anddiverse implicit quantitative parameters are involvedare susceptible of being treated using technical ofgeoprocessing tools which facilitate in great measurethe obtaining of derived products. For the case of thepresent study, the obtaining of the Map of Vulnerabilityto the Contamination of an Aquifer uses the techniquedenominated Algebra of Maps. In this process to eachparameter mapped are assigned numeric values to beable to be used in an equation whose solution will bethe derived product of interest, at the end, this numericresult is changed in polygons defined accordingto the resulting values obtaining this way the newcartography.