In order to know better the groundwater quality of Salento, chemical-physical and microbiological investigations were carried out on waters collected from 31 wells chosen after a preliminary study about the hydrogeologic features of the region. The analysis, conducted once in a month within the span of a year, pointed out a widespread contamination of faecal origin, which limits the employment (drinkable, irriguous) of groundwater because of possible health implications. The results of the chemical-physical analyses show how the groundwater of Salento is "contaminated" by sea water getting into the continent and which in some areas, also owing to excessive drawings, deteriorates its quality and compromises its irriguous use.