When Can Babies Drink Water? An Age-by-Age Guide

No Water Before 6 Months — and Here's Why

For babies under 6 months, breast milk or formula provides all the fluid they need — even in hot weather. Giving extra water is not just unnecessary; it's dangerous. Infant kidneys are immature and cannot process large amounts of free water. This can dilute blood sodium levels, causing a potentially life-threatening condition called hyponatremia (water intoxication) (AAP, 2023).

If your baby seems hot or fussy in warm weather, the answer is more nursing — not water. The composition of breast milk shifts to meet hydration needs.

After 6 Months: Small Amounts Are Fine

Once solid foods are introduced, small amounts of water can be offered — primarily to introduce cup drinking rather than as a significant hydration source.

• 6–12 months: Up to 4–8 oz (120–240 ml) per day, offered in a small open cup or sippy cup at mealtimes.
• 1–3 years: 1–4 cups per day depending on activity and diet.
• Avoid juice: The AAP recommends no juice before 12 months — the sugar content offers no nutritional advantage over whole fruit.

Signs of Dehydration

Signs your baby is well hydrated: 6+ wet diapers per day, tears when crying, moist mouth and lips. Warning signs: sunken fontanelle (soft spot), no tears, dry mouth, fewer than 6 wet diapers in 24 hours, sunken eyes — seek medical care promptly.