Quick Answer
For babies under 6 months, water is not recommended and can be harmful. Breast milk and formula provide all the hydration a young baby needs. From 6 months, when solid foods are introduced, small sips of water with meals are appropriate and encouraged. The amount increases gradually as your baby's solid food intake grows. Water should complement milk feeds, not replace them, throughout the first year.
Under 6 Months: No Water Needed
Breast milk and formula are both approximately 87 to 88 percent water. They provide complete hydration for a baby under 6 months, along with all the nutrition they need. Giving water to a baby under 6 months is not just unnecessary, it can be actively harmful:
- Water intoxication: A baby's kidneys are immature and cannot process large amounts of water. Even relatively small quantities can dilute the sodium in the blood to dangerous levels, causing a condition called hyponatraemia, which can lead to seizures and, in severe cases, be life-threatening
- Reduced milk intake: Water fills the stomach without providing any nutrition. A baby who has had water may take less breast milk or formula, reducing their calorie and nutrient intake at a stage when growth demands are very high
- Reduced milk supply: For breastfeeding parents, fewer breast feeds means less stimulation and a potential reduction in milk supply
The only exception is in very hot weather, where your pediatrician may advise small amounts of water for formula-fed babies. Always follow your pediatrician's guidance.
From 6 Months: Introducing Water With Solids
When solid foods are introduced at around 6 months, small amounts of water with meals become appropriate. As your baby begins eating food, they need water to help with digestion and to stay hydrated as their diet diversifies. Guidelines generally suggest:
- 6 to 12 months: Up to 120 to 180ml (4 to 6 oz) of water per day, offered in small sips with meals. This is in addition to breast milk or formula, which remains the primary source of nutrition and hydration throughout the first year
- 12 months onwards: Water intake can increase as milk feeds reduce and solid food intake grows. From 12 months, whole cow's milk can replace formula, and water becomes the primary drink alongside milk
How to Offer Water to a Baby
- Use an open cup or a free-flow sippy cup: From 6 months, the NHS and many paediatric guidelines recommend introducing an open cup or a free-flow cup rather than a valve sippy cup. Open cups support healthy oral development and help babies learn to sip rather than suck
- Offer water with meals, not between: Offering water with meals rather than between feeds helps preserve appetite for milk and solid food
- Use cooled boiled water until 12 months: For babies under 12 months, use water that has been boiled and allowed to cool. From 12 months, tap water is generally safe without boiling in most developed countries
- Do not add anything to the water: No juice, squash, sugar, or flavouring. Plain water is the goal
Signs Your Baby May Need More Fluids
- Fewer wet nappies than usual (fewer than 6 wet nappies per day in a young baby is worth monitoring)
- Dark yellow urine
- Dry mouth or lips
- Unusual lethargy or irritability in hot weather
If you are concerned about dehydration at any age, contact your pediatrician promptly.
What About Juice?
Fruit juice is not recommended for babies under 12 months. Even 100 percent fruit juice contains significant amounts of sugar and provides no nutritional benefit that cannot be obtained from whole fruit or milk. After 12 months, if juice is offered at all, it should be limited to 120ml per day of 100 percent fruit juice, diluted with water, and offered with meals rather than as a drink throughout the day.
Key Takeaway
No water before 6 months. From 6 months, small sips of water with meals are appropriate and encouraged as solid foods are introduced. Breast milk or formula remains the primary source of hydration and nutrition throughout the first year. Use an open cup or free-flow cup, offer cooled boiled water, and keep it plain. Water complements milk feeds; it does not replace them.
Parents Also Ask
When Can Babies Start Eating Solid Foods?
How Do I Know If My Baby Is Getting Enough Milk?
Could Gas Be Making My Baby Uncomfortable During Feeds?
This article is for informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult your pediatrician or a qualified healthcare provider with questions about your baby's health.