Children aged 4–8 need about 1.3 liters of drinks per day, 9–13-year-olds need 1.5–1.9 L, and teenagers 1.9–2.6 L. Sport, heat and school days without easy water access all push these numbers higher.
Children's fluid needs scale with body size and activity, not with a single universal number. The European Food Safety Authority publishes adequate intakes for total water; the figures below are the portion that should come from drinks, with the rest supplied by food.
By late adolescence, needs are essentially adult, and body weight becomes the better guide — roughly 33 ml per kilogram as a baseline.
Children have more skin surface area relative to their body mass, so they gain heat from the environment more quickly. Their sweating response is less efficient than an adult's, and — most practically — they are absorbed in play and simply do not stop to drink. Thirst arrives after the fact, and children act on it less consistently than adults do.
Most under-drinking in children happens between 8 am and 3 pm. Water access is restricted, breaks are short, and some children avoid drinking to avoid asking to use the toilet. A refillable bottle on the desk, where permitted, is the single most effective intervention. Aim for:
Add 150–250 ml for every 20–30 minutes of active sport, and offer a drink before the activity starts rather than only afterwards. On hot days, add 300–500 ml across the day even without sport. For activity under an hour, water is sufficient — sports drinks add sugar without benefit for most children.
Water and milk are the defaults. Juice counts as fluid but should be capped at roughly 120–150 ml daily and served with meals. Soft drinks and energy drinks add sugar and, in the case of energy drinks, caffeine that is not appropriate for children. Herbal teas are fine when unsweetened and not too hot.
Dark urine, fewer than four bathroom visits a day, dry lips, headaches, irritability and unusual tiredness are the common signals. In infants and toddlers, fewer wet nappies, no tears when crying, or a sunken soft spot are urgent signs that need medical attention rather than home management.
Around 1.5 litres of drinks per day for girls and 1.6–1.9 litres for boys aged 9–13, according to EFSA. Add 300–500 ml on days with sport or hot weather.
Yes. Children have a larger surface area relative to body mass, sweat less efficiently at high temperatures, and are less likely to notice or act on thirst while playing.
Both count as fluid. Milk is a good option nutritionally; juice should be limited to about 120–150 ml per day because of sugar content. Water should be the default drink between meals.
Dark urine, fewer than four bathroom trips a day, dry lips, unusual tiredness or irritability. In young children, reduced tears when crying and fewer wet nappies are stronger warning signs and warrant medical advice.