Can drinking more fluids help prevent recurring urinary tract infections (UTIs)? Until recently, no one had looked. So scientists at Danone Research—Danone sells bottled water—randomly assigned 140 premenopausal women to drink either an extra 1½ liters (about 6 cups) of water a day or no more water than usual. (All the women had been diagnosed with at least three UTIs in the previous year and all typically drank less than 1½ liters of fluids a day before the study started.)