At 10 months old, your baby can have small sips of water, but the total should stay modest. Most pediatric guidelines suggest limiting water to about 2 to 4 ounces (roughly 60 to 120 mL) per day for babies between 6 and 12 months. Breast milk or formula remains your baby’s primary source of both hydration and nutrition until their first birthday.
Why the Limit Is So Low
Your baby’s stomach is small, and every ounce of water takes the place of breast milk or formula. Those feeds deliver the calories, protein, fat, vitamins, and minerals that fuel your baby’s rapid growth. Water has none of that. Giving too much water effectively dilutes your baby’s calorie intake across the day, which can slow weight gain at a stage when steady growth is one of the most important markers of health.
There’s also a more serious risk. Excess water can dilute the sodium in a baby’s bloodstream, a condition called hyponatremia (sometimes called water intoxication). Babies are more vulnerable to this than older children because their kidneys are still maturing and can’t flush large volumes of water efficiently. Symptoms include unusual irritability or excessive sleepiness, puffiness around the eyes, low body temperature, and in severe cases, seizures. This is rare when water is offered in small, supervised sips, but it’s the reason the daily limit exists.
How Water Fits Into Your Baby’s Day
Think of water at 10 months as a companion to solid food meals, not a standalone drink. Offering a few sips from a cup during breakfast, lunch, or dinner is a good habit. Between meals and away from the highchair, breast milk or formula should still be the go-to.
A practical approach: fill a small open cup or straw cup with an ounce or two of water and let your baby practice drinking with their meal. You don’t need to track every milliliter. If the total stays in the neighborhood of a few ounces across the whole day, you’re in the right range.
Practicing With a Cup
Ten months is a great age to work on cup skills. Most babies at this stage can sit independently, hold objects with both hands, and bring things to their mouths, which are the key readiness signs. An open cup (the kind without a lid) is ideal for developing the coordination of sipping and swallowing, though it will be messy at first.
You can help by lifting the cup to your baby’s lips and tilting it gently so they get a small sip. Keep your baby seated and supervised. Be patient if they dribble most of it out or seem uninterested. It often takes a few days of consistent practice before they get the hang of it. A straw cup is another good option and tends to be less spillage-prone while still building oral motor skills differently than a bottle.
Tap Water, Bottled Water, and Fluoride
Plain tap water is fine for a 10-month-old in most areas. Many community water systems add fluoride, which supports dental health as your baby’s teeth come in. At this age, the small risk of mild fluorosis (faint white marks on teeth from too much fluoride) that applies to very young formula-fed infants is less of a concern, since your baby is older and the volume of water is low.
If your tap water isn’t fluoridated, your pediatrician may eventually recommend a fluoride supplement. Bottled water is fine to use, but check the label: some brands contain fluoride and some don’t, so it’s worth knowing what you’re working with.
What About Juice and Other Drinks?
The American Academy of Pediatrics recommends completely avoiding fruit juice before a child’s first birthday. Juice offers no nutritional benefit over whole fruit at this age, and it can displace breast milk or formula in the same way water does, with the added downside of excess sugar. The same goes for sweetened drinks, teas, and broths. For now, the only beverages your baby needs are breast milk or formula and those few ounces of plain water.
Hydration During Illness or Hot Weather
When your baby has a fever, diarrhea, or is vomiting, dehydration becomes a real concern. Your instinct might be to offer extra water, but for babies under one year, the recommended approach is different. Breast milk, formula, or a pediatric oral rehydration solution are all better choices because they replace both fluids and electrolytes.
If your baby is having trouble keeping fluids down, try offering very small amounts frequently: 1 to 2 teaspoons of breast milk, formula, or rehydration solution every 5 to 10 minutes. Plain water on its own isn’t ideal during illness because it doesn’t replace the salts and sugars your baby is losing, and in larger volumes it could worsen an electrolyte imbalance. Signs of dehydration to watch for include fewer wet diapers than usual, no tears when crying, a dry mouth, and unusual fussiness or lethargy.
What Changes at 12 Months
Once your baby turns one, the fluid picture shifts. You can begin offering whole cow’s milk (or a fortified unsweetened dairy alternative) alongside regular meals, and water becomes a more routine part of the day. Toddlers between 12 and 24 months generally do well with about 1 to 4 cups of water daily, depending on their diet, activity level, and climate. The tight restrictions on water loosen because by that point, your child is getting most of their nutrition from solid foods rather than relying so heavily on milk feeds for every calorie and nutrient.
For the next two months, though, keep doing what you’re doing: small sips of water with meals, breast milk or formula as the main event, and no juice or sweetened drinks. Your baby is building the foundation of healthy drinking habits one messy cup at a time.