Water is found in many sources, which is why the U.S. Department of Agriculture's guidelines for a child's water needs include both beverages and food. Water is in fruits and vegetables, ice cream, soup, yogurt, milk, tea, coffee, juice and soda, among others. It's impossible for you to calculate the exact amount of water your child gets per day. Offer up plenty of drinking water and water-rich foods and watch him for signs of dehydration.
0 to 1 Year
Unless your pediatrician tells you otherwise, you don't need to feed a young baby water. As long as breast milk or formula is his main form of nutrition, a baby gets all the fluid he needs, according to HealthyChildren. Don't introduce water until you introduce solid foods, the site advises.
Even then, water shouldn't be a substitute for breast milk or formula. Once a baby is 6 months old, pediatrician Dr. Alan Greene suggests giving him 2 to 4 ounces of water if he seems thirsty between feedings.
1 to 3 Years Old
As your baby's diet expands and he gets less fluid from breast milk or formula, he requires more water from other sources. According to the USDA, a child between the ages of 1 and 3 needs a total of 5 1/2 cups of water per day. At this age, he should get about 4 cups of water from beverages and 1 1/2 cups of water from foods daily.
4 to 8 Years Old
A child's water needs grow as his body does. Between the ages of 4 and 8, a child needs a total of about 7 cups of water per day. That's 5 cups of water from beverages and 2 cups of water from foods.
9 to 13 Years Old
These are the ages at which boys' and girls' hydration needs start to vary. A girl this age needs a total of 9 cups of water per day, with 7 cups coming from beverages and 2 cups from food. A boy needs 10 cups total. He should be getting 2 cups of water from food and 8 cups from beverages.
14 to 18 Years Old
Girls between 14 and 18 require a total of 10 cups of water per day, 8 cups of which should come from beverages and 2 from food. Boys this age need 14 cups of water, 11 cups from beverages and 3 cups from food.
Factors Affecting Water Needs
A child's height, weight, metabolism and activity level as well as the weather conditions all influence his exact fluid needs, and those needs can vary day by day. An 8-year-old boy who plays soccer outdoors on a hot day will need more water than an 8-year-old boy who spends the day playing video games.
Certain medical conditions such as diabetes and kidney disease also influence a child's fluid needs. If your child has such a condition, discuss his hydration with your pediatrician.
By the time your child is thirsty, he's already becoming dehydrated. Additional signs of dehydration include dry mouth, irritability, dark yellow urine, less frequent urination than normal, constipation and headaches. Giving your child as much water to drink as he wants can typically reverse mild dehydration.
Call the pediatrician immediately if you notice signs of severe dehydration, which include extreme thirst, extreme fussiness, little or no urine production, sunken eyes, rapid heartbeat or breathing and fever.
Illnesses including fevers, colds, vomiting and diarrhea can also cause dehydration.