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Can babies drink water?

Babies under 6 months should not be given plain water, since their kidneys can't handle extra fluid and it can cause dangerous sodium imbalances. From about 6 months, once solids start, small amounts of water can be offered in a cup.

After 6 months, water is mainly used to practice cup drinking and isn't meant to replace breast milk or formula as the main source of hydration and nutrition.

Strength of evidence

Strong

This is based on consistent national guidelines from the Canadian Paediatric Society, American Academy of Pediatrics, CDC, and NHS, all agreeing on timing and safety limits, though the underlying risk data come mainly from older case reports and physiology rather than recent trials.

What the evidence says

For the first 6 months, babies get all the fluid they need from breast milk or formula. Giving extra water in this period isn't just unnecessary, it can be risky: a young baby's kidneys aren't mature enough to handle extra water, and too much can dilute their blood sodium, leading to problems like seizures in serious cases.

Once your baby starts solid foods around 6 months, you can begin offering small sips of water from an open or straw cup, generally about 4 to 8 ounces (roughly half to one cup) a day. This is more about practicing cup skills and getting used to the taste of water than actual hydration, since breast milk or formula should still be the main drink.

If you're formula feeding, always mix formula with the exact amount of water the instructions say. Adding extra water to stretch formula, or giving your baby plain water on top of formula before 6 months, can lead to the same dangerous sodium imbalance.

Canadian guidance (Canadian Paediatric Society) matches this: introduce small amounts of water once or twice a day after your baby starts solids around 6 months, and skip juice at this age. There's no meaningful difference between Canadian and American guidance on this point.

Sources

✓Reviewed by CH, MD, FRCPC

Reviewed by a specialist physician certified by the Royal College of Physicians and Surgeons of Canada, who has read this answer against the sources listed above and confirmed it reflects them. That is not medical advice about your child. How we review

Answer checked July 31, 2026

Educational information only. Not medical advice, not a diagnosis, and no doctor-patient relationship is created by using this. Founded Parent has not examined your child and does not know their history, so this may not apply to you. In an emergency, call your local emergency number. What Founded Parent cannot do

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