Why do infants have a greater need for water than older humans?

Infants’ bodies contain more water (75%) than those of older humans. Their kidneys are not fully mature yet thus they excrete more diluted urine. This cause easy dehydration and a higher risk of illness for infants. Infants are less resistant to heat since their thermoregulatory systems are not as developed. Parents and caregivers must see to it that infants are provided water for their hydration.