Water for Babies: When and How Much Is Safe
Last updated June 2026 · Reviewed by Nibli Editorial Team
A clear, evidence-based guide to introducing water safely once your baby starts solids around 6 months.
Water feels like the most natural drink in the world, so many parents are surprised to learn that babies don't need it for the first few months of life. Until around 6 months, breast milk or infant formula provides all the fluid your baby needs, even in hot weather. Offering extra water too early can be genuinely risky, so timing matters.
Once your baby starts solid foods at around 6 months, small sips of water from an open cup become a helpful and healthy addition to mealtimes. At this stage water supports digestion as your baby's diet expands, helps with constipation, and gives your little one a chance to practice the important new skill of cup drinking.
This guide explains exactly when babies can have water, how much is appropriate, why an open cup is recommended over a sippy or bottle, and how to think about tap versus bottled water. It also covers why juice and other sweet drinks aren't needed. As always, these are general guidelines, so check in with your pediatrician or health visitor about your individual baby.
Key takeaways
- Babies under 6 months need only breast milk or formula; extra water can cause dangerous low sodium (water intoxication).
- Introduce small sips of water from an open cup once solids start around 6 months.
- There's no daily quota; a few sips up to about 2 oz (60 ml) a day is plenty at first.
- An open or free-flow cup beats a valved sippy cup for speech, feeding skills, and teeth.
- Offer water at mealtimes; keep milk as the main drink throughout the first year.
- Safe tap water works well; under 6 months boil and cool it, and never over-boil.
- Skip juice and sweet drinks entirely in year one; choose whole fruit and plain water.
When Can Babies Start Drinking Water?
For healthy, full-term babies, the simple rule is: no extra water before 6 months. From birth to around 6 months, breast milk or formula supplies all the hydration and nutrition your baby needs. This stays true during heat waves and minor illnesses too, where the answer is usually to offer more frequent milk feeds rather than water.
From around 6 months, as your baby begins eating solid foods, you can start offering small amounts of water alongside meals. There's no need to push it, and many breastfed babies in particular take very little at first. The goal early on is gentle exposure and practice, not hitting a fluid target.
If your baby is premature, has a medical condition, or your doctor has given specific instructions, follow that advice instead of the general timeline. The same goes for any formula-feeding questions about extra fluids, where your health visitor or pediatrician is the best guide.
- Under 6 months: only breast milk or formula, no plain water needed
- Around 6 months with solids: introduce small sips from an open cup
- Hot weather under 6 months: offer extra milk feeds, not water
- Premature or medically complex babies: follow your doctor's advice
Why Water Can Be Dangerous for Young Infants
It can seem harmless, but giving plain water to a baby under about 6 months can lead to a serious condition. A young infant's kidneys are still immature and cannot process large volumes of water efficiently. Too much water dilutes the sodium and other electrolytes in the blood, a condition called hyponatremia, sometimes described as water intoxication.
Low sodium can cause symptoms ranging from irritability, drowsiness, and a low body temperature to swelling and, in severe cases, seizures. Because a small baby is little, it does not take much extra water to tip the balance. This is why pediatric guidance is so firm about avoiding plain water in the early months.
Extra water can also fill a tiny tummy and reduce the amount of milk a baby drinks, which means fewer calories and less nutrition for growth. For these reasons, save water for around the 6-month mark when solids begin, and never dilute infant formula with extra water beyond the manufacturer's instructions.
- Immature kidneys can't handle large water volumes in young babies
- Too much water lowers blood sodium (hyponatremia / water intoxication)
- Warning signs can include drowsiness, irritability, low temperature, or swelling
- Always mix formula exactly as the label directs, never extra-diluted
How Much Water Does a Baby Need?
Once solids begin around 6 months, there's no strict daily quota of water for babies, and you don't need to measure it. Small sips offered with meals are plenty at first. A common, gentle starting point is just a few sips up to a couple of ounces (around 30 to 60 ml) spread across the day, with breast milk or formula still the main drink throughout the first year.
As your baby grows and eats more solid food across the second half of the first year, water intake naturally increases, but milk feeds should remain central until 12 months. Let your baby lead, and avoid encouraging large volumes of water, which can blunt appetite for nutrient-rich milk and food.
After the first birthday, water (and whole cow's milk, if appropriate) can become a more established part of the day. If you ever have concerns about how much your baby is drinking or about their growth, your pediatrician or health visitor can reassure you and check things over.
- From 6 months: a few sips up to roughly 2 oz (60 ml) of water a day is typical
- Breast milk or formula stays the main drink through the first year
- Don't force water; let your baby sip to their own comfort
- Water intake naturally rises as solids increase
Open Cup vs Sippy Cup
When introducing water, an open cup (or a small free-flow cup without a valve) is the recommended choice. Drinking from an open cup helps develop the lip, tongue, and jaw coordination your baby needs for speech and eating, and it encourages mature sipping and swallowing rather than the sucking pattern used with bottles.
Sippy cups with hard spouts and valves require sucking and, when used constantly throughout the day, can bathe the teeth in liquid and contribute to dental problems. Health authorities generally suggest moving away from bottles and avoiding reliance on no-spill valved cups, aiming for your child to be off the bottle by around 12 to 18 months.
Open-cup drinking is messy at first, and that's completely normal. Start with a tiny amount of water in the bottom of the cup, help your baby tip it gently, and expect plenty of dribbles while the skill develops. A baby-sized cup, a doidy (slanted) cup, or a small open cup all work well.
- Open or free-flow cups support speech and feeding development
- Avoid relying on hard-spout, valved sippy cups all day long
- Aim to phase out bottles by around 12 to 18 months
- Expect mess at first; offer just a little water to practice with
Offering Water With Meals
Mealtimes are the easiest and most natural time to offer water. Putting a small open cup on the highchair tray alongside food lets your baby take sips as they eat, helps wash down new textures, and builds a healthy habit of drinking water with food rather than reaching for sweet drinks.
Water with meals can also help with the constipation that sometimes appears when babies first start solids, as the digestive system adjusts to new foods. Combined with fibre-rich options like fruit, vegetables, and whole grains, a little water can keep things comfortable.
Between meals, breast milk or formula remains the go-to drink in the first year. You don't need to offer water constantly throughout the day; a cup at mealtimes (and a little extra in hot weather once over 6 months) is usually all that's needed.
- Offer a small open cup of water with each solid meal
- Sips help wash down new textures and ease early constipation
- Keep milk feeds as the main drink between meals in year one
- Hot weather: a little extra water is fine once your baby is on solids
Signs Your Baby Is Well Hydrated
Most parents worry about whether their baby is getting enough fluid, but reassuringly, a baby who is feeding well on breast milk or formula is almost always well hydrated. The clearest everyday sign is regular wet nappies with pale, mild-smelling urine, typically around six or more wet nappies a day in a thriving baby.
Other signs of good hydration include a moist mouth and tongue, tears when crying, alert and settled behaviour, and steady weight gain over time. You don't need to add water to keep a young baby hydrated, so focus on responsive, frequent milk feeds.
It's worth knowing the signs of dehydration so you can act quickly if your baby is unwell, especially with vomiting, diarrhoea, or fever. If you notice any of these, contact your doctor or health visitor promptly, as babies can become dehydrated faster than older children.
- Six or more wet nappies a day with pale, mild-smelling urine
- Moist mouth, tears when crying, and alert behaviour
- Dehydration warning signs: fewer wet nappies, dark urine, dry mouth, sunken soft spot, drowsiness, no tears
- Seek medical advice quickly if your baby is unwell or showing these signs
Tap Water, Bottled Water, and Boiling Basics
In most areas with a safe public supply, tap water is a fine choice for babies. For babies under 6 months, water used to make up formula or to drink should be boiled and then cooled. After 6 months, healthy babies who are simply drinking sips of water with meals generally no longer need it boiled, though it's sensible to check local guidance.
Avoid over-boiling water or re-boiling the same water repeatedly, because this can concentrate minerals. Boil fresh water once, let it cool, and use it. If you choose bottled water, pick a still (non-fizzy), low-mineral option and check the sodium content is low (ideally well under 200 mg per litre); some natural mineral waters are too high in minerals for babies. Most bottled waters are not sterile, so for babies under 6 months they should still be boiled and cooled before use.
On fluoride: many tap supplies contain fluoride, which helps protect teeth, while levels vary by location and bottled waters often contain little or none. There's no need to seek out or avoid fluoridated water specifically for hydration. If you have questions about fluoride and your baby's dental health, your dentist, pediatrician, or health visitor can advise based on your local water.
- Safe tap water is suitable; under 6 months, boil and cool it first
- After 6 months, sips of water with meals usually don't need boiling
- Don't over-boil or repeatedly re-boil water (it concentrates minerals)
- Choose still, low-sodium bottled water; it isn't sterile, so boil for under-6-month use
- Ask your dentist or doctor about fluoride and your local supply
Why Juice and Sweet Drinks Aren't Needed
Babies simply don't need fruit juice, squash, flavored milks, or any sugary or fizzy drinks. Major pediatric guidance recommends no fruit juice at all in the first year, and only small, limited amounts (if any) for toddlers, always from a cup and ideally with meals. Whole fruit is a far better choice than juice, providing fibre and fullness without a rush of free sugars.
Sweet drinks can crowd out milk and food, contribute to tooth decay, set up a preference for sweet flavours, and add unnecessary calories. Even drinks marketed for babies and toddlers can be high in sugar, so it's worth reading labels carefully and being cautious.
Stick to breast milk or formula in the first year, plus small sips of plain water with meals once solids begin. After 12 months, water and (where suitable) plain whole milk are the everyday drinks to offer. This keeps your baby's teeth healthy and their appetite tuned to nourishing food.
- No fruit juice in the first year; offer whole fruit instead
- Avoid squash, flavored or sweetened milks, and fizzy drinks
- Sweet drinks promote tooth decay and crowd out milk and food
- Plain water and milk are the only drinks young children need
Frequently Asked Questions
Can I give my newborn water in hot weather?
No. Babies under about 6 months should not be given plain water, even in hot weather. Instead, offer more frequent breast milk or formula feeds, which provide all the hydration they need. Giving water to a young infant can dangerously dilute their blood sodium. If you're worried your baby is overheating or not feeding well, contact your doctor or health visitor.
At what age can babies start drinking water?
Healthy, full-term babies can start having small sips of water from an open cup at around 6 months, when they begin eating solid foods. Before 6 months, breast milk or formula supplies all the fluid they need. Always offer water in addition to milk feeds, not as a replacement for them, during the first year.
How much water should a 6-month-old drink?
There's no strict amount. A few sips up to roughly 2 ounces (about 60 ml) of water across the day is typical once solids begin, mostly offered at mealtimes. Breast milk or formula should remain the main drink. Let your baby sip to their own comfort rather than encouraging large volumes, which can reduce their appetite for nutritious milk and food.
Should I use an open cup or a sippy cup for water?
An open cup or a free-flow cup without a valve is recommended. Open-cup drinking helps develop the mouth muscles your baby needs for speech and eating and encourages mature sipping. Hard-spout valved sippy cups require sucking and, if used all day, can contribute to tooth decay. It's messy at first, so start with just a little water to practice.
Does my baby need extra water if they're constipated?
Once your baby is on solids, offering small sips of water with meals can help ease the constipation that sometimes appears when starting solid foods, alongside fibre-rich fruits, vegetables, and whole grains. For babies under 6 months, don't give water; speak to your doctor or health visitor about constipation, as the approach is different in young infants.
Can I give my baby fruit juice?
Fruit juice is not recommended in the first year at all, and only small amounts (if any) for toddlers, always from a cup and ideally with meals. Whole fruit is a better choice because it provides fibre and fullness without concentrated sugars. Juice and other sweet drinks can promote tooth decay and crowd out milk and nourishing food.
Is tap water or bottled water better for babies?
In areas with a safe public supply, tap water is a good, convenient choice. For babies under 6 months, water for drinking or making formula should be boiled and then cooled first. If you prefer bottled water, choose a still, low-sodium option (ideally well under 200 mg sodium per litre); because most bottled water isn't sterile, it should also be boiled and cooled for babies under 6 months.
Do I need to boil water for my baby?
For babies under 6 months, yes, boil water and let it cool before using it for drinking or to make up formula. After 6 months, healthy babies simply taking sips of water with meals generally no longer need it boiled, though it's wise to check your local guidance. Avoid over-boiling or repeatedly re-boiling water, as this can concentrate minerals.
What are the signs my baby is getting enough fluid?
A well-hydrated baby usually has around six or more wet nappies a day with pale, mild-smelling urine, a moist mouth, tears when crying, alert behaviour, and steady weight gain. A baby feeding well on breast milk or formula is almost always well hydrated. Watch for dehydration signs such as fewer wet nappies, dark urine, a dry mouth, or drowsiness, and seek medical advice promptly if your baby is unwell.
Can drinking water fill my baby up too much?
Yes, especially for younger babies. Water has no calories, so drinking a lot can blunt your baby's appetite for the breast milk, formula, and solid food that fuel their growth. That's why water is offered in small sips with meals during the first year while milk remains the main drink. If your baby seems to prefer water over milk or food, mention it to your pediatrician.
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