 Acute dehydration in the elderly is a well-known clinical condition, although situations that lead to chronic dehydration in the elderly may be quite frequent, but they are poorly studied. Metabolic changes in body water homeostasis can influence and provide chronic dehydration status as reduced sensitivity to thirst, antidiuretic hormone and renal inability to concentrate urine and the presence of chronic diseases and the use of polypharmacy may also predispose states of chronic dehydration. Due to these facts, a study to detect the existence of chronic dehydration states in a population of elderly people is highly justifiable. In addition, understanding whether increased water intake, improving chronic dehydration, may improve renal function in this population seems to be of great value, since it is a simple and inexpensive intervention and, if confirmed, it can be taken to institutions, by family members and health promoters who care for and cohabit with elderly individuals. 