Babies can start drinking small amounts of water at 6 months old. Before that age, breast milk or formula provides all the hydration and nutrition an infant needs, even in hot weather. The World Health Organization and other major health authorities recommend exclusive breastfeeding (or formula feeding) for the first six months of life, with no supplemental water.
Why Babies Under 6 Months Don’t Need Water
Breast milk is about 87% water, and infant formula is similarly high in water content. Both provide complete hydration for a young baby’s needs. Giving water to a baby younger than 6 months can fill up their tiny stomach, displacing the breast milk or formula that delivers calories, protein, fat, and essential vitamins. Since young infants have limited stomach capacity, even a few ounces of water can meaningfully reduce the amount of nutrition they take in.
A common concern is whether babies need extra water during hot weather. A systematic review published in Frontiers in Pediatrics found no evidence that infants under 6 months require supplementary fluids in hot conditions. Exclusively breastfed infants maintained normal hydration levels even in heat, without concentrating their urine to maximal levels. The takeaway: if your baby is feeding well and producing regular wet diapers, they’re getting enough fluid from milk alone.
How Much Water at 6 to 12 Months
Once your baby turns 6 months old and starts eating solid foods, you can begin offering water. The CDC recommends 4 to 8 ounces per day for babies between 6 and 12 months. That’s roughly half a cup to one cup total throughout the day, not all at once. Water at this stage is more about practice and getting used to the taste than about meeting hydration needs. Breast milk or formula still remains the primary source of nutrition and fluids during this period.
Think of water as a complement to meals rather than a replacement for milk feeds. A few sips with solid food is a good starting point. You don’t need to stress about hitting a specific number of ounces. Most babies will naturally drink what they need if water is offered regularly alongside meals.
Best Ways to Offer Water
When you start introducing water at 6 months, it’s also a great time to introduce a cup. Many parents reach for a sippy cup, but spouted sippy cups require the same sucking motion as a bottle and don’t actually teach new drinking skills. A better choice is a small open cup or a lidded cup with a straw, both of which help your baby develop more advanced mouth coordination.
Start by putting just a few sips of water in the cup to minimize spills. Hold the cup with your baby and gently guide it to their mouth. If they push it away or seem uninterested, that’s normal. Take a break and try again at the next meal. If you do use a sippy cup for convenience, aim to transition to an open cup by your baby’s first birthday.
Is Tap Water Safe for Babies?
In most cases, regular tap water is safe for preparing formula and for offering to babies who are 6 months and older. If you’re unsure about your local water quality, your health department can provide testing information. Filtered or unfiltered tap water is generally fine.
Extra precautions apply when mixing powdered formula for babies under 2 months, premature infants, or babies with weakened immune systems. In these cases, boiling water and letting it cool for about five minutes before mixing with formula helps kill bacteria like Cronobacter that can sometimes be present in powdered formula. Always test the temperature on your wrist before feeding: it should feel warm, not hot.
During emergencies like floods or water main breaks, use bottled water if available. If bottled water isn’t an option, boiling tap water and cooling it to room temperature makes it safe for mixing formula. One important exception: water contaminated with chemicals or toxins cannot be made safe by boiling or filtering. In those situations, use bottled water or ready-to-feed formula.
After 12 Months
Once your child turns one, water becomes a more important part of daily hydration. Toddlers are typically eating a wider variety of solid foods and gradually weaning off formula or breast milk. You can offer water freely throughout the day, and most toddlers will drink when they’re thirsty if a cup is accessible. Plain water and plain milk are the best drink choices at this stage. Juice, flavored waters, and sugary drinks aren’t necessary and can displace more nutritious options.
A good rule of thumb for toddlers is to keep a small cup of water within reach during meals and snacks, and to offer it more frequently during hot weather or active play. Children are generally good at self-regulating their fluid intake as long as water is available.