By the Peanutbean parent · checked against CDC, NHS and AAP guidance · how we fact-check

When can babies drink water?

Last verified: July 18, 2026

Illustration of an open baby cup with water and a small droplet

The short answer: babies do not need water for roughly the first 6 months. Breast milk or first infant formula gives them all the fluid they need, even in summer. From around 6 months, when solid foods start, you can offer sips of water from an open cup with meals. There is one exception: formula-fed babies under 6 months may have small sips of cooled boiled water in hot weather.

Why young babies do not need water

For the first 6 months of life, milk is both food and drink. The NHS puts it plainly: breast milk is the only food or drink babies need in the first 6 months (NHS: Drinks and cups for babies and young children). First infant formula is the only suitable alternative during that time.

The World Health Organization says the same thing at a global level. Its guidance recommends exclusive breastfeeding for the first 6 months, and it spells out that this means not giving babies additional food or drink, even water, unless it is medically necessary (WHO: Infant and young child feeding).

So if a well-meaning relative suggests a bottle of water for a 2-month-old on a warm day, you can relax and say no. Milk covers it.

What about hot weather?

This is where the advice splits by how your baby is fed, and the difference is worth knowing:

Fully breastfed babies do not need any water until they have started solid foods. In hot weather they may simply want to breastfeed more often than usual, and that extra milk is their extra fluid (NHS).
Formula-fed babies under 6 months may need small sips of cooled boiled water during hot weather, as well as their usual milk feeds (NHS).

Note the wording: small sips, on top of normal feeds, not instead of them. Milk stays the main event.

From 6 months: sips with meals

Once your baby starts solid foods at around 6 months, you can offer sips of water from a cup or beaker with meals. Two practical details from the NHS make life easier:

Drinking water for babies over 6 months does not need to be boiled first. Tap water is fine.
An open cup, or a free-flow cup without a valve, is better than a bottle or a valved beaker. It teaches your baby to sip rather than suck, and it is better for their teeth (NHS).

Expect mess. That is normal and it passes. Water at mealtimes is about practice as much as thirst at this stage, because milk still provides most of what your baby drinks until they are eating plenty of solids.

If you are wondering how milk feeds change as solids ramp up, our guide on how much milk your baby needs walks through it month by month.

Drinks to skip in the first year

Water and milk are the only drinks your baby needs. The NHS is specific about the rest:

Fruit juice and smoothies: babies under 12 months do not need them. If you choose to offer them anyway, dilute 1 part juice to 10 parts water and keep them to mealtimes, because the natural sugars and acids can cause tooth decay.
Squash, fizzy drinks, flavoured milk, and “fruit” drinks: not suitable for babies. Even diluted, the sugar can damage teeth, and fizzy drinks are acidic on top of that.
Rice drinks: children under 5 should not have them because of the arsenic levels found in rice products.
Tea and coffee: not suitable for babies or young children.
“Baby” and herbal drinks: these usually contain sugars and are not recommended (NHS).

Cows’ milk has its own timeline: fine in cooking from around 6 months, but not as a main drink until 12 months, because it does not have the right balance of nutrients for a baby.

When to call your doctor

Water itself rarely causes an emergency, but fluid problems in babies can. Talk to your GP, health visitor, or call 111 if:

your baby is showing signs of dehydration, such as noticeably fewer wet nappies than usual
your baby is feeding much less than normal, or refusing feeds
your baby seems unusually sleepy or hard to wake alongside feeding changes
your baby has a fever and is not keeping fluids down (see our baby fever guide for the exact thresholds)

Wet nappies are the honest signal that a baby is getting enough fluid. And as always, your own concern is reason enough to call.

Keep reading

Sources

NHS: Drinks and cups for babies and young children (page last reviewed October 2022)
WHO: Infant and young child feeding (fact sheet, December 2023)

Peanutbean provides general information for educational purposes only. It is not medical advice. Every baby develops at their own pace. Always talk to your pediatrician about your child’s health.

Common questions

Can I give my newborn water in hot weather?

If your baby is fully breastfed, no. They do not need any water until they start solid foods, though they may want to breastfeed more often in the heat. Formula-fed babies under 6 months may have small sips of cooled boiled water in hot weather, on top of their usual milk feeds.

Does my baby's water need to be boiled?

Once your baby is over 6 months, drinking water straight from the tap is fine and does not need boiling first. Water used to make up formula is different: that still needs to be prepared following the NHS guidance on making up formula safely, whatever your baby's age.

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