Quick Answer
Babies under 6 months should not be given water. Before 6 months, breast milk or formula provides all the hydration a baby needs, and introducing water in this period carries a genuine risk of water intoxication, a serious condition in which excess water dilutes the sodium in the blood to dangerous levels. From 6 months, small sips of water alongside solid foods are appropriate and can be introduced gradually. After 12 months, water becomes an important part of the daily diet and can be offered freely. The transition from no water to small sips to free access is a gradual developmental progression tied closely to the introduction of solid foods.
Why No Water Before 6 Months
The recommendation against water before 6 months is not conservative caution; it is grounded in the physiology of the young infant. Before 6 months, a baby's kidneys are immature and cannot process excess water effectively. When water is given, it dilutes the sodium and other electrolytes in the bloodstream, which can lead to hyponatraemia (low blood sodium), a condition that in severe cases causes seizures, brain damage, and in rare cases death.
Even small amounts of water given regularly to a young baby can displace breast milk or formula from the diet, reducing the intake of calories and nutrients that the baby depends on for growth. Water has no nutritional value for an infant under 6 months and poses a physiological risk that breast milk and formula do not.
The only exception is in medically supervised situations, such as specific medical conditions or documented guidance from a pediatrician. Outside of a medical recommendation, water before 6 months is not appropriate regardless of weather, temperature, or the baby appearing thirsty. A breastfed or formula-fed baby who is hot or appears thirsty should be offered more breast milk or formula, not water.
6 to 12 Months: Small Sips Alongside Solids
From 6 months, when solid foods are introduced, small amounts of water can be offered alongside meals. At this stage, water is not a replacement for breast milk or formula, which remain the primary source of nutrition and hydration throughout the first year. The purpose of offering water at meals is to help babies become familiar with drinking from a cup and to support digestion as higher-fibre solid foods are introduced.
The recommended amount of water for babies 6 to 12 months is small: around 2 to 4 oz (60 to 120ml) per day alongside meals is sufficient. Offering water from an open cup or a soft-spout sippy cup at mealtimes introduces the skill of cup drinking in a natural, low-pressure context. Straw cups are also an option from around 9 months when the oral motor skills needed to use them are typically in place.
Breast milk or formula should continue to be offered on demand throughout this period. Water should complement rather than displace milk feeds.
What Type of Water Is Safe for Babies
The type of water offered matters:
- Tap water: In areas with safe, treated municipal water supplies, tap water is appropriate for babies from 6 months. If you are unsure about your local water quality, check with your local water authority or use a filtered alternative
- Filtered water: A certified water filter that removes contaminants is a suitable option if tap water quality is uncertain
- Bottled water: If using bottled water, choose a still (not sparkling) variety low in sodium (less than 200mg per litre). Sparkling water is not appropriate for babies
- Well water: Well water should be tested before being given to babies, as it may contain elevated levels of nitrates or other contaminants not present in treated municipal supplies
Water used to prepare formula for babies under 12 months should be boiled and cooled to eliminate bacteria, even if the tap water is considered safe for drinking.
After 12 Months: Water as Part of the Daily Diet
After 12 months, water can and should be offered freely throughout the day. As whole cow's milk or a milk alternative takes over from formula or breast milk as the primary dairy drink, water becomes the primary hydration drink. Juice, sweetened beverages, and flavoured drinks are not recommended for children under 2 years and should be offered minimally (if at all) to older toddlers.
From 12 months, a daily intake of around 8 oz (240ml) of water is a reasonable starting target, increasing with age, activity level, and weather. Children who are eating a varied diet of fruits and vegetables will also obtain significant hydration from their food.
Signs Your Baby May Need More Hydration
For babies under 6 months who are exclusively breastfed or formula-fed, dehydration is addressed by offering more feeds rather than water. Signs that a baby in this age group may need more milk include:
- Fewer than the expected number of wet nappies (typically 6 or more per day after the first week)
- Dark yellow or concentrated urine
- Dry mouth or lips
- Sunken fontanelle (the soft spot on the top of the head)
- Unusual lethargy or reduced responsiveness
These signs warrant a call to your pediatrician rather than offering water to a baby under 6 months. For babies 6 months and older who are eating solids, mild dehydration during illness or hot weather can be supplemented with small additional amounts of water alongside increased milk feeds.
Key Takeaway
No water before 6 months: breast milk or formula provides complete hydration and water poses a genuine risk of electrolyte imbalance in young infants. From 6 months, offer small sips of water (2 to 4 oz per day) alongside solid foods to introduce cup drinking and support digestion, while continuing breast milk or formula as the primary drink. After 12 months, water can be offered freely throughout the day and becomes the primary hydration drink alongside whole milk. Use tap, filtered, or low-sodium still bottled water; avoid sparkling water and sweetened drinks for babies and toddlers.
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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 nutrition and hydration.