Objectives: The relationship of water intake with kidney function in the population is uncertain. This study investigated cross-sectionally and longitudinally the relationship of the intake of water and other beverages with kidney function within an adult Italian population sample. Methods: In 4,554 Gubbio Study examinees (54.4% women, age 18-95 years), data collection at baseline included demographics, anthropometry, questionnaires on habitual intakes of water and other beverages (non-water fluids), a timed overnight urine collection, estimated glomerular filtration rate (eGFR), decreased eGFR ( , 60 mL/minute/1.73 m2), and other variables including urinary markers of diet. At 15-year follow-up, the incidence of renal/kidney replacement th...