Babies can start drinking small amounts of water at around 6 months old, once they begin eating solid foods. Before that age, breast milk or formula provides all the hydration they need. The target for babies 6 to 12 months is 4 to 8 ounces per day, which is roughly half a cup to one cup. That’s not much, and it doesn’t need to be. Water at this stage is more about building a habit than meeting a hydration goal.
Why Babies Under 6 Months Shouldn’t Have Water
Young infants have immature kidneys that can’t process extra water efficiently. Giving water to a baby under 6 months risks a condition called water intoxication, where sodium levels in the blood drop rapidly. This causes cells to swell, particularly in the brain, and can lead to seizures, irritability, or drowsiness. It doesn’t take a large amount of water to trigger this in a small body. A rapid increase of just 7 to 8 percent in total body water is enough to cause symptoms.
There’s also a practical concern: water fills a baby’s stomach without providing any calories or nutrients. Newborns who drink water may breastfeed less often, which can slow weight gain, contribute to jaundice, and reduce a mother’s milk supply since the baby isn’t nursing as frequently.
How Much Water Between 6 and 12 Months
Once your baby is eating solid foods, typically around 6 months, you can offer 4 to 8 ounces of water per day. Breast milk or formula should still be the primary source of nutrition and hydration during this period. Water is a complement, not a replacement. If your baby only takes a few sips at first, that’s completely fine. The goal is exposure and practice, not hitting a specific volume.
After 12 months, water intake naturally increases as your child transitions away from formula or breast milk and eats more table food. Toddlers generally need more water, but for babies in that 6 to 12 month window, a few ounces throughout the day is plenty.
Choosing the Right Cup
Offer water in an open cup, sippy cup, or straw cup rather than a bottle. Babies as young as 6 months can start practicing with these, and the earlier they’re introduced, the easier the transition away from bottles later on. Open cups build oral motor skills, though they’re messy at first. Straw cups are a good middle ground since they’re portable and spill less while still encouraging a more mature drinking pattern than a bottle nipple.
One helpful strategy is to let your baby hold and explore the cup before you expect them to drink from it. Offer an empty cup during bath time or play so it becomes a familiar object. When you’re ready to add water, put just a small amount in the cup during mealtimes while your baby is seated in a high chair. Show them how it works by taking a sip yourself or tilting the cup gently toward their lips.
Getting a Reluctant Baby to Try Water
Some babies simply aren’t interested, especially if they’re getting plenty of breast milk or formula. This is normal. A few approaches can help:
- Offer it consistently at meals. Place the cup of water on the high chair tray at every meal so it becomes part of the routine. Even if they ignore it for days, the familiarity builds.
- Try different cups. Some babies prefer a straw, others like tipping an open cup. If one style isn’t working, switch it up.
- Keep it room temperature or slightly cool. Very cold water can be startling. Lukewarm or room temperature water is often accepted more easily.
- Model drinking. Babies imitate what they see. Drink water from a similar cup in front of them.
For older babies and toddlers who resist plain water, you can add mild natural flavor by infusing water with fruit. Cucumber and watermelon, strawberry and lemon, or blueberries and raspberries are simple combinations. Let the fruit sit in the water, then strain it before serving so there are no choking hazards. Avoid adding honey to water for any child under 1 year old, and skip herbal teas for babies entirely.
Tap Water vs. Bottled Water
Fluoridated tap water is generally the best choice for babies because the fluoride supports developing teeth. You can use non-fluoridated bottled water occasionally, but tap water should be the primary source when it’s safe in your area. For babies under 2 months, premature infants, or those with weakened immune systems, boil the water first and let it cool for about 5 minutes before use. For healthy babies 6 months and older starting on water for the first time, this precaution typically isn’t necessary if your tap water is safe.
Signs Your Baby Is Getting Enough Fluids
Since water intake at this age is small, you don’t need to stress about counting ounces. Instead, watch for signs of adequate hydration. Six to eight wet diapers per day is normal for a well-hydrated baby. Fewer than three or four wet diapers a day signals possible dehydration.
Other dehydration warning signs include a sunken soft spot (the fontanelle on top of the head), no tears when crying, extreme sleepiness, feeding less than usual, and unusual irritability or listlessness. These signs are more likely to appear during illness, hot weather, or if a baby is refusing to eat, rather than from simply not drinking enough water on an ordinary day. If your baby is nursing or taking formula normally and producing plenty of wet diapers, their hydration is almost certainly fine regardless of how much plain water they accept from a cup.