When can babies drink water?

Under 6 months: no extra water

Healthy babies under 6 months don’t need water. Breast milk or formula gives them all the fluid they need. On hot days, the NHS says breastfed babies may simply want to feed more often. If you’re formula feeding and worried about heat, ask your pediatrician or health visitor (see the US and UK differences below).

Extra water can be harmful at this age. The AAP explains that it fills a baby up, so they take less of the milk they need to grow. Too much water can also upset the balance of salts like sodium in the body, which can lead to serious problems, including seizures. This is sometimes called water intoxication.

The same goes for formula: always mix it exactly as the label says. Never add extra water to make formula go further. If you’re having trouble affording formula, the AAP suggests asking your pediatrician, local health department, a food pantry or a social service agency for help.

From 6 months: sips with meals

Once your baby starts solid food, around 6 months, you can offer water in a cup with meals. The AAP and CDC suggest up to 4–8 oz (120–240 ml) a day in total, from 6 to 12 months.

At this age, water is mostly about learning to drink from a cup and getting used to the taste. It won’t replace much breast milk or formula, and it shouldn’t: breast milk or formula is still the main drink.

• Offer a few sips with each meal, as the NHS suggests.
• Let your baby stop when they want. Many babies drink very little at first.
• If you live in an area with fluoridated tap water, drinking it also helps protect your baby’s teeth, according to the AAP.

Which cup to use

Both US and UK guidance encourage a cup over a bottle for water.

• From about 6 months: an open cup, a free-flow cup (one without a valve), a straw cup, or a spouted training cup.
• From about 9 months: the CDC says babies can start learning to use a cup without a lid.
• Around 12 months: most children can drink from an open cup while you hold it.

Expect spills. That’s part of learning.

From 12 months: water as the main drink

From 12 months, the AAP suggests about 8–32 oz (240–950 ml) of water a day, alongside plain milk. Water and plain milk are the only drinks young children need. The AAP’s guide for 12–24 months is whole cow’s milk, about 16 oz (480 ml) a day. See what to feed at 12 months.

How much water your toddler drinks will vary with the weather, how active they are, and how much milk they have. Offer it with meals and snacks, and whenever they seem thirsty.

Drinks to skip

• Cow’s, goat’s or sheep’s milk, or plant drinks, as a main drink before 12 months (CDC, NHS). Small amounts of pasteurized cow’s milk in cooking are fine from about 6 months (NHS). The CDC says not to give cow’s milk before 12 months. If you follow US advice, use breast milk or formula instead. Never give unpasteurized (raw) milk.
• Juice: none before 12 months (AAP, CDC). After that, it isn’t needed, and the AAP’s limit for ages 1–3 is 4 oz (120 ml) of 100% juice a day. Whole fruit is the better choice.
• Sugary drinks, including sweetened or flavored water, squash, soda and juice drinks.
• Drinks with low-calorie sweeteners, like diet drinks.
• Tea, coffee and other drinks with caffeine.
• Rice drinks: the NHS says not before 5 years, because of arsenic.

Hot weather

In very hot weather, the AAP says babies who have started solids may need a little extra water. Keep offering breast milk or formula as usual too.

Call your pediatrician right away if your baby shows signs of dehydration:

• fewer wet diapers than usual
• being unusually sleepy
• a sunken soft spot on the top of the head
• no tears when crying

If your baby is very limp, hard to wake or unresponsive, or keeps vomiting, call 911 or go to the emergency room.If your baby is very limp, hard to wake or unresponsive, or keeps vomiting, call 999 or go to A&E.If your baby is very limp, hard to wake or unresponsive, or keeps vomiting, call your local emergency number (such as 112 in Europe or 000 in Australia) or go to the nearest emergency department.

Is tap water safe for babies?

For drinking, the NHS says water for babies over 6 months doesn’t need to be boiled. The AAP says safe tap water is fine for mixing formula unless your local water supply is known to be contaminated, and to use a water source your state or local government defines as safe. If you use well water or aren’t sure, check with your local health department.

The rules for mixing formula are stricter, and they differ between the US and UK: see the boiling-water point below.

Where US and UK advice differs

• Water under 6 months. The AAP says no extra water before 6 months unless your pediatrician advises it. The NHS agrees for breastfed babies, but says formula-fed babies under 6 months may need small sips of cooled boiled water in hot weather, as well as their usual feeds.
• Cups. The AAP is fine with open, sippy or straw cups. The NHS recommends an open cup or a free-flow cup without a valve, which it says is better for teeth.
• Boiling water for formula. In the US, the AAP says to boil water for formula for babies under 2 months, babies born early, and babies with a weakened immune system; otherwise, safe tap water can be used. In the UK, the NHS says to make up every formula feed with freshly boiled tap water that has cooled for no more than 30 minutes, so it’s still at least 70°C, and it doesn’t usually recommend bottled water for formula. Elsewhere, follow the formula label and your local health service’s advice.
• Juice under 12 months. The AAP and CDC say none. The NHS says babies don’t need it, but if you do give it, dilute it (1 part juice to 10 parts water) and only at mealtimes.

For how drinks fit into the day, see the baby feeding schedule.