The U.S. Department of Agriculture recommends different amounts of water based on age, sex and health status 1. The specific recommendations are based on the amount of water lost on a daily basis through perspiration, respiration, urination or metabolism. The USDA began setting dietary recommendations for water to help individuals avoid dehydration. The USDA recommendation is higher for those who live in hot, humid climates and for those who engage in prolonged exercise.
People need from under one liter a day to nearly four liters a day depending on their age, sex and health status. One liter equals 4.23 cups. Newborns and infants need 0.7 to 0.8 liters of water a day from breast milk or formula. Toddlers need 1.3 liters and young children up to eight years need 1.7 liters daily. Boys, ages nine to 13 need 2.4 liters daily. Teenage boys and adult men need 2.7 liters. Girls, ages nine to 13 need 2.1 liters and teenage girls need 2.3 liters. Adult women need at least 2.7 liters of water each day. Women need at least 3 liters of water during pregnancy and 3.8 liters daily for lactation.