When can I give my baby water?

Olivia Howell’s son, Weston, was four months old when her grandmother told her to give him a bottle filled with water to cool him down when it was warm in the house. “I guess she gave water to her own babies,” says Howell. Howell wasn’t sure giving her formula-fed baby a bottle of water was a good idea, but she didn’t know for sure that she shouldn’t, so she went ahead and offered it to him. But Weston didn’t really go for its bland taste after he’d come to expect formula.

Howell was right to question her grandmother’s advice: Up to six months of age, babies get all the water they need from breastmilk or formula. And while you might think a bit of cool water on a hot day won’t do any harm—after all, we know it’s the healthiest drink for kids and adults—it can be detrimental to your infant’s health. “Giving a baby water at that age interferes with feeding and can lead to poor weight gain,” says paediatrician Catherine Pound, the chair of the Canadian Paediatric Society’s nutrition committee. With breastmilk or formula, they get the calories and nutrients they need, but if you fill up their tummies with water, there won’t be enough room left for proper nutrition.

Keeping your baby hydrated

Becky Blair, a public health dietitian who represented Dietitians of Canada in writing the most recent nutrition guidelines for infants, says this recommendation holds true even when it’s hot or humid outside. But, she adds, dehydration is a serious condition, and if you think your baby isn’t getting enough liquid, you should contact your doctor. You can tell your baby is well-hydrated by counting their wet diapers. Between the ages of six days and six months, a baby should have at least six heavy, wet diapers a day. Some signs of dehydration include having fewer bowel movements than normal, being excessively fussy or sleepy, having sunken eyes or wrinkled skin, or having cool, discoloured hands and feet.

So when should you start giving your baby water? The ideal time is after your little one reaches six months and you start introducing solid food. But don’t worry if your baby doesn’t drink too much at first—this is normal because they are getting used to the new taste. They should still be receiving most of their hydration from breastmilk or formula until at least a year.

Blair recommends serving the water in an open-top cup. “The purpose of the water in an open cup is just to allow infants to practise drinking.” Sippy cups—although ubiquitous among babies and toddlers—are not actually recommended for regular drinking because they don’t let your baby gain more mature swallowing skills. Blair says they are fine, however, for on the go or for keeping near the crib at night. “Parents should avoid giving any liquid other than water in a sippy cup to their infant,” she advises. Having a milk- or juice-filled sippy hanging around can lead to the child mindlessly consuming sugary drinks.

How much water should a baby have?

While there are no specific guidelines for how much water to give your baby, Blair suggests starting off with just a few tablespoons and then increasing to about a quarter- or a half-cup when she is a year old. And rest assured, municipal tap water is just fine for your little one, and there’s no need to filter the water. But, Blair says, “if you use well water, make sure your water meets current safety standards, particularly for nitrates, and don’t use water that’s gone through a water softener, because that contributes additional sodium.” She says parents should avoid mineral water, which contains sodium; carbonated water, which makes babies gassy; and vitamin and “baby waters,” which make unsubstantiated claims about being healthier but haven’t been tested in infants.

When can my baby drink juice?

Just because you’re introducing water doesn’t mean it’s time to rush into giving other drinks, like juice. “Juice is really not necessary,” says Pound. “It’s just sugar.” She advises that if you are going to give it to them, make sure it’s real fruit juice, and offer no more than four ounces a day. Once your baby is over six months, water really is the healthiest choice, so getting them used to it—and not sugary beverages—when they’re babies can set them up for success.

Read more: How I finally got my baby to take a bottle An age-by-age guide to your baby's eating habits