For many years now, the investigators research unit has been involved in projects, partially financed by the Italian Ministry of University and Research (MIUR), geared towards studying the effects induced by dietary changes in patients with calcium stone disease. The aim of the present project is to analyse in depth the relationship between stone disease, hypertension, body weight and water and salt intake both in the general population of the area of Parma (where historically and by gastronomic tradition, the usual diet tends to have a high salt content) and in a selected population of stone formers and hypertensives not under treatment. A representative sample of the population of the area of Parma will be studied, divided on the basis of weight category, in order to assess water and salt intake and relationships with the presence of hypertension, and a sample of normal and hypertensive stone formers randomized to receive for one year either water therapy+low salt diet or water therapy alone.