The work is a synthesis of the qualitative monitoring on waters resources (specially surface water), that were potable and distributed as drinkable waters in north Sardinia between 1996-2002. The obtained results point out: for the surface waters, recurrent problems of elevated turbidity, color, oxidability, microbial contamination and eutrofication; for the ground waters, lower levels of pollutants even if an high content of natural elements and substances that, for as of natural origin, could endanger and limit the use as drinkable water (sodium, chlorides, iron, manganese). Drinking water plants have, largely, solved the main causes of ineffectiveness of treatment such as the demolition of the organic load and the formation of trihalomethanes but it as been found an high concentration of chlorites; occasionally, the values of ammonia, aluminum, iron, manganese and, rarely, trihalomethanes are out law in piped.