DEFINITION OF A MODEL FOR MONITORING THE CHEMICAL AND CHEMICAL-PHYSICAL CHARACTERISTICS OF DEEP DRINKING WATERS.

A probabilistic model was utilized for the chemical and chemical-physical characterization of deep drinking waters of the Perugia province (Umbria region, Italy). Factor analysis applied to several parameters indicated ten factors, but the first three had the greatest share of variance. In the first factor the most important parameters are calcium, hardness (total, temporary and permanent), solid residue, electric conductivity, pH, sulfates and magnesium; in the second, turbidity, suspended substances and aluminum; and in the third, potassium and phosphates. The cluster analysis applied to these parameters confirmed the relationships found by factor analysis except for the pH in the first group and aluminum in the third one. Another cluster analysis, applied to several drinking water sources, grouped the samples in three clusters. In the first cluster are 407 sources located mainly in the characteristic hills of the Umbria region and in the valleys of the principal rivers. The second groups 310 sources located mainly in the mountains of the Apennines and the third 36 sources located mainly where the river Tiber valley joins the Umbria valley. The chemical and chemical-physical characters relative to the three clusters are consistent with the geo-morphological characteristics of the territories from which the waters came.