Children ages 1 to 3 need about 4 cups of water a day, while older kids and teens need anywhere from 5 to 8 cups depending on age and sex. These numbers cover plain water and other beverages, not counting the water naturally found in food. The right amount shifts as your child grows, and it changes further with activity level, weather, and diet.
Daily Water Needs by Age
Here’s what children need in total daily fluids from beverages (water, milk, juice, etc.):
- Ages 1 to 3: About 4 cups (1 liter)
- Ages 4 to 8: About 5 cups (1.2 liters)
- Boys 9 to 13: About 6 cups (1.6 liters)
- Girls 9 to 13: About 5 to 6 cups (1.4 liters)
- Boys 14 to 18: About 7 to 8 cups (1.9 liters)
- Girls 14 to 18: About 6 cups (1.6 liters)
These figures represent beverage intake only. Roughly 20% of a child’s total water intake comes from food, especially fruits, vegetables, soups, and yogurt. A child who eats a lot of watermelon, oranges, and cucumbers is getting a meaningful boost toward their daily needs without drinking anything extra.
Plain water should make up the bulk of what your child drinks. Milk contributes to the total, and small amounts of diluted juice count too, but water is the simplest and healthiest way to keep kids hydrated throughout the day.
Why Babies Under 6 Months Shouldn’t Drink Water
Babies younger than 6 months should get all their fluids from breast milk or formula. Their kidneys are too immature to process extra water safely, and even small amounts of plain water can dilute sodium levels in the blood to dangerous concentrations. This condition, called water intoxication, happens when total body water rises by roughly 7% to 8% or more, causing cells in the brain to swell.
The signs of water intoxication in an infant include confusion, drowsiness, muscle twitching, nausea, vomiting, difficulty breathing, and weakness. In severe cases it can lead to seizures, brain damage, or coma. The risk is highest in very young infants because their powerful hunger drive can lead them to accept water readily, even though their bodies can’t handle it. Once your baby reaches 6 months, small sips of water alongside solid foods are fine, but breast milk or formula remains the primary source of hydration through the first year.
Hydration During Sports and Physical Activity
Active kids need significantly more fluid than the baseline recommendations. Heat, humidity, and the intensity of exercise all increase how much water your child loses through sweat, and children are less efficient at regulating body temperature than adults.
A practical approach, based on guidelines from Johns Hopkins Medicine: have your child drink 16 to 24 ounces of water or a sports drink about two hours before activity. During exercise, kids ages 9 to 12 should aim for 3 to 8 ounces every 20 minutes. Teens ages 13 to 18 need more, roughly 11 to 16 ounces every 20 minutes.
For activities lasting over an hour, a sports drink can help replace the sodium and electrolytes lost through sweat. Plain water works well for shorter sessions. After exercise, 16 to 24 ounces of fluid helps with recovery, and the ideal target is about 24 ounces for every pound of body weight lost during the activity. You can check this by weighing your child before and after practice on a hot day to get a sense of how much they typically sweat.
Signs Your Child Isn’t Drinking Enough
Most mild dehydration is easy to fix once you notice it. In infants and toddlers, the clearest early sign is fewer wet diapers. If your baby hasn’t had a wet diaper in three hours or more, that’s a signal to increase fluids. Other signs in young children include a dry mouth, no tears when crying, sunken eyes or cheeks, and unusual crankiness or low energy. A sunken soft spot on the top of a baby’s skull is another reliable indicator.
In older kids, watch for dark yellow urine, infrequent bathroom trips, dry or cracked lips, headaches, and fatigue. A simple urine color check works well: pale yellow means well hydrated, while dark amber suggests your child needs to drink more. One physical sign that applies to all ages is the skin pinch test. If you gently pinch the skin on the back of your child’s hand and it doesn’t flatten back immediately, dehydration may be more than mild.
Practical Ways to Help Kids Drink More
Many children simply forget to drink, especially during school hours when access to water depends on bathroom and fountain breaks. Sending your child to school with a labeled, refillable water bottle gives them consistent access. For younger kids who resist plain water, adding a few slices of fruit like strawberries, cucumber, or orange can make it more appealing without adding significant sugar.
Building water into routine moments helps too. A cup of water at every meal and snack creates a baseline of 4 to 5 drinking opportunities a day without anyone having to think about it. For picky drinkers, offering water-rich snacks like grapes, celery sticks, or frozen fruit popsicles made at home supplements what they’re getting from the cup. Keeping water visible and accessible, rather than stored in the fridge behind other drinks, makes it the default choice.
Temperature matters for some kids. Younger children often prefer room-temperature water, while older kids and teens tend to drink more when it’s cold. Experimenting with both can make a surprising difference in how much your child actually finishes.