Hydration for Kids & Teens: A Parent's Complete Guide

Children are not just small adults when it comes to hydration. Their bodies contain a higher proportion of water, their metabolic rate is faster, they generate more heat during exercise, and they often do not recognize or communicate thirst effectively. This guide walks parents through age-specific water needs, signs of dehydration in children, and practical strategies for building healthy drinking habits.

Age-Specific Water Requirements

The Institute of Medicine (IOM) and the European Food Safety Authority (EFSA) provide age-based guidelines for total water intake from all beverages and foods. Infants under 6 months need approximately 700 ml per day, which should come exclusively from breast milk or formula — no additional water is needed and giving plain water can actually be dangerous at this age because infant kidneys cannot handle excess free water. Infants 7 to 12 months need about 800 ml per day, with the majority still from breast milk or formula and small amounts from solid foods and water.

Children 1 to 3 years old need about 1.3 liters per day from all sources. Children 4 to 8 years old need about 1.7 liters per day. Girls 9 to 13 need 2.1 liters and boys 9 to 13 need 2.4 liters. Teenage girls 14 to 18 need 2.3 liters and teenage boys 14 to 18 need 3.3 liters — the same range as adult women and men, reflecting their near-adult size and metabolic rate. Roughly 20 percent of this comes from food, with the remaining 80 percent from beverages.

These are baseline recommendations for sedentary children in temperate climates. Active kids, kids playing sports, and kids in hot climates need more. A child playing soccer for an hour in summer heat may need an additional 500 to 1,000 ml of water to replace sweat losses. Use your judgment based on the child's activity level, the weather, and the color of their urine (pale straw color indicates good hydration).

Signs of Dehydration in Children

Children show dehydration differently than adults, and the signs can be subtle. Infants and toddlers cannot tell you they are thirsty, so parents and caregivers must watch for physical signs. In infants, look for: no wet diaper for 3 hours or more; sunken soft spot (fontanelle) on top of the head; sunken eyes or cheeks; dry mouth and tongue; crying without tears; unusual sleepiness or fussiness; cool, blotchy hands and feet.

In older children, signs include: dark yellow urine or no urination for 6 to 8 hours; dry mouth and lips; headache; fatigue or unusual quietness; dizziness when standing; irritability; reduced sweating during play; and dry, cool skin. Children with vomiting or diarrhea are at particularly high risk of dehydration because they are losing fluids rapidly and may not be able to keep fluids down. In these cases, offer small sips of an oral rehydration solution (like Pedialyte) frequently rather than large amounts of plain water.

Severe dehydration in children is a medical emergency. Seek immediate medical attention if a child shows: extreme fussiness or sleepiness that cannot be roused; sunken eyes; no urination for 8 hours or more (or no wet diaper for 6 hours in infants); rapid breathing or heartbeat; cold, splotchy hands and feet; confusion; or fainting. Intravenous fluids may be needed.

Building Healthy Drinking Habits Early

The habits children form around beverages often persist into adulthood. Parents play a crucial role in establishing water as the default beverage. Here are evidence-based strategies for building healthy hydration habits in children. First, offer water with every meal and snack. Make water the standard beverage at the family table, with milk as an alternative for growing kids. Limit juice to 120 ml per day for young children and 240 ml for older kids, and always choose 100 percent fruit juice rather than juice drinks with added sugar. Avoid soda, sports drinks, and energy drinks entirely for young children.

Second, make water easily accessible. Keep a child-sized water bottle or cup within reach. For toddlers, a sippy cup or straw cup with water available throughout the day encourages sipping. For school-age kids, send a refillable water bottle to school and ask them to refill it at lunch. Many schools now have water bottle filling stations, making this easier than ever.

Third, model the behavior you want to see. Children learn by watching their parents. If they see you drinking water regularly, they are more likely to do the same. If they see you reaching for soda or sweet tea whenever you are thirsty, they will internalize that as normal. Make water visible and desirable in your home.

Fourth, flavor water naturally if your child resists plain water. Slices of cucumber, strawberry, lemon, lime, or fresh mint make water more appealing without adding sugar. Let your child help prepare the infused water — kids are more likely to drink what they helped make. Avoid artificially flavored water enhancers, which often contain artificial sweeteners and may perpetuate a preference for sweet beverages.

Hydration for Young Athletes

Children and teenagers who play sports have higher hydration needs than their sedentary peers. Kids generate more heat per unit of body weight during exercise than adults, and they sweat less efficiently, which means their core temperature rises faster. The American Academy of Pediatrics recommends that young athletes drink 100 to 250 ml of water every 20 minutes during exercise, with the higher end for older and larger kids.

For exercise lasting less than 60 minutes, plain water is sufficient. For longer activities, especially in heat, a sports drink with 6 to 8 percent carbohydrate and electrolytes can help maintain blood glucose and replace sodium lost in sweat. Avoid energy drinks entirely — the high caffeine content is unsafe for children and teenagers. Coaches and parents should encourage drinking during practice and games rather than relying on thirst, since children often do not recognize thirst until they are significantly dehydrated.

Weighing young athletes before and after practice can help determine individual sweat rates. Each kilogram of weight lost equals roughly 1 liter of fluid that needs replacing. Coaches should be trained to recognize signs of heat illness and to adjust practice intensity in hot, humid conditions. For more detail, see our complete hydration and exercise guide.

Special Considerations

Children with certain medical conditions have special hydration needs. Kids with diabetes insipidus, cystic fibrosis, kidney disease, or gastrointestinal conditions may need carefully managed fluid intake. Children taking certain medications, particularly diuretics or lithium, may also need adjusted hydration. Always follow the specific guidance of your child's healthcare provider for these situations.

In hot weather, increase fluid intake and watch for signs of heat illness. Children should not exercise intensely in temperatures above 32 degrees Celsius (90 degrees Fahrenheit) with high humidity. Schedule outdoor play for early morning or evening in summer, and provide shade and water breaks every 20 minutes. For our complete summer safety guide, see our article on summer hydration safety.