When Can Babies Drink Water?
Babies under 6 months should never be given water. After 6 months, small amounts of water (2–4 oz/day) can be introduced alongside solid foods. Breast milk or formula remains the primary source of fluid until at least 12 months.
Key Takeaways
- Babies under 6 months should never be given water — breast milk and formula provide complete hydration (WHO, AAP, NHS)
- Even small amounts of water can cause hyponatremia (water intoxication) in newborns — a potentially life-threatening electrolyte imbalance
- From 6 months, offer 2–4 oz (60–120 ml) of water per day with meals in an open cup or straw cup
- Water should never replace breast milk or formula, which remain the primary fluids until 12 months
- Juice is not recommended before 12 months — water and milk are the only appropriate drinks for babies
Why No Water Before 6 Months
This is a firm medical guideline from WHO, AAP, and NHS:
1. Kidneys Cannot Process Extra Water
Newborn kidneys are immature. They cannot concentrate or dilute urine effectively. Extra water overwhelms this system.
2. Water Intoxication (Hyponatremia)
Giving too much water dilutes sodium levels in the blood — a condition called hyponatremia. In infants, this can cause:
- Irritability or lethargy
- Puffiness
- Seizures
- Brain damage
- Death (in extreme cases)
This is rare but serious. Even small amounts of water given repeatedly to a newborn can cause electrolyte imbalance.
3. Nutritional Displacement
Breast milk and formula are calorie-dense. Water has zero calories. If a baby drinks water and feels "full," they drink less milk — risking inadequate calorie and nutrient intake.
Water Introduction Timeline
| Age | Water | Notes |
|---|---|---|
| 0–6 months | ❌ None | Breast milk or formula provides all hydration |
| 6 months | ✅ Small amounts (2–4 oz/day) | With meals, in open or straw cup |
| 6–12 months | ✅ 4–8 oz/day max | Alongside breast milk/formula |
| 12 months | ✅ Freely offered | Can transition to cow's milk as main drink |
How to Introduce Water at 6 Months
- Use an open cup (not a sippy cup with valve), helps with oral development
- Or a straw cup, also great for development
- With meals, a few sips with solid food introduction
- Tap water is fine in most developed countries (if local water quality is good)
- No juice, no nutritional benefit; high sugar content
- Room temperature or slightly cool, not very cold
Signs of Dehydration in Babies
Even on an all-milk diet, dehydration can occur (illness, hot weather, insufficient feeding):
Mild-moderate dehydration:
- Fewer wet diapers (fewer than 6/day)
- Dark yellow urine
- Dry mouth and lips
- Slightly sunken fontanelle (soft spot)
Severe dehydration (emergency):
- No wet diaper for 8+ hours
- No tears when crying
- Very dry mouth
- Extremely sunken eyes/fontanelle
- Lethargic, unresponsive
If you suspect dehydration, call your pediatrician immediately.
After 12 Months: Water as Main Drink
From 12 months:
- Water can and should be the main offered drink (besides milk)
- Full-fat cow's milk: up to 400ml (14 oz) per day
- Juice: avoid or limit to 4 oz/day of 100% juice maximum (AAP 2024)
- No sugary drinks, sports drinks, or flavored water
🔗 See our Baby Hydration Guide and Cup Introduction Tips for more.
Sources: WHO. Infant Feeding Guidelines; American Academy of Pediatrics (AAP). Water and Juice for Infants; NHS UK. Drinks for Babies and Young Children; Pediatrics, "Water Intoxication in Infancy"
Frequently Asked Questions
When can babies drink water?
Babies under 6 months should not be given any water — not even small sips. After 6 months, when solid foods begin, small amounts of water (2–4 oz / 60–120 ml per day) can be offered with meals. This recommendation is consistent across WHO, AAP, and NHS guidelines.
Can you give a newborn water?
No. Giving water to a newborn or baby under 6 months is dangerous. Their kidneys cannot process excess water, which can dilute sodium levels in the blood and cause hyponatremia — potentially leading to seizures, brain damage, or death in extreme cases. Breast milk and formula provide all the hydration a baby needs.
How much water should a 6-month-old drink?
At 6 months, just a few sips (2–4 oz / 60–120 ml) per day with meals. Water at this age is for practice and to supplement solids — not to replace breast milk or formula. Breast milk or formula remains the primary fluid until 12 months.
Does my baby need extra water in hot weather?
No. Healthy babies under 6 months do not need water even in hot weather. Breast milk is approximately 87% water and provides complete hydration. Breastfeeding parents should offer the breast more frequently in heat. Formula-fed babies can receive their normal formula amount more often.
What type of cup should I use when introducing water?
The NHS recommends an open cup (beaker) or free-flow sippy cup from 6 months to support oral development and reduce prolonged bottle use. Avoid sippy cups with non-spill valves, which require sucking rather than sipping. In countries with safe tap water (US, UK, most of Europe), boiling is not necessary after 6 months.
Sources
- AAP — Infant and toddler nutrition guidelines
- WHO — Global infant feeding recommendations
- CDC — Infant and toddler nutrition resources
🔧 Helpful Tools
- Baby Food Guide — Safe foods and introduction schedule for your baby
- Breastfeeding Tracker — Log feeds, track supply, and monitor nursing sessions
- All Baby Tools — Browse all free tools for pregnancy and baby care
