Question: how much water should an average 13 year old drink?
Answer: Girls and boys between 4 and 8 years old should drink 40 ounces per day, or 5 cups. This amount increases to 56–64 ounces, or 7–8 cups, by ages 9 to 13 years. For ages 14 to 18, the recommended water intake is 64–88 ounces, or 8–11 cups.