Drinking guide
When can babies drink water?
It is one of the strangest facts of the first year: the safest drink on earth is the one your baby is not supposed to have. Water waits until around 6 months, and the reason is worth understanding, because it also explains how much to offer once you start.
Why newborns cannot have water at all
General pediatric guidance, including from the American Academy of Pediatrics, is that water is introduced at around 6 months and not before. There are two reasons, and they are both about size.
The first is the kidneys. A young baby’s kidneys are still developing and cannot clear a surplus of water efficiently. Too much water dilutes the sodium in the blood, which can cause a rare but serious condition sometimes described as water intoxication. It does not take much in a body that small.
The second is the stomach. A newborn stomach holds very little, so every ounce of water is an ounce of breast milk or formula that did not go in. Water has no calories, no protein, and no fat, and in the first months every feed is doing developmental work. This is why the advice holds even on hot days: the usual guidance for a hot day is more frequent milk feeds, not water.
How much water, by age
| Age | Water | Main drink |
|---|---|---|
| 0 to 6 months | None | Breast milk or formula, on demand |
| 6 to 12 months | Small amounts with meals, about 4 to 8 oz a day | Still breast milk or formula |
| 12 to 24 months | Freely with meals and snacks, inside roughly 4 cups of fluids a day | Whole milk plus water |
These are the ranges in common pediatric guidance, not targets to hit. Babies vary, weather varies, and a toddler who drank three cups yesterday and one today is a normal toddler. Your pediatrician knows your baby and is the right person to ask about amounts.
At 6 months, water is really cup practice
Here is the part that surprises most parents: between 6 and 12 months, the water is not doing much hydrating. Breast milk or formula is still the main drink for the whole first year. What the water is doing is giving your baby something safe and consequence-free to practice drinking with, at exactly the age when the skill is worth building.
That reframes the whole thing. You are not trying to get water into your baby. You are handing them a cup with an ounce in it and letting them work out what a rim is for. Some of it lands in their mouth. Most of it does not, at first. Both outcomes are the lesson.
Which cup to use for a baby’s first water
- Start with a tiny open cup. The First Cup (2oz) is sized so that a full pour is still a small spill. Open cup drinking uses the same lip, tongue, and jaw coordination as mature swallowing, which is why feeding professionals tend to favor it early.
- Move to a weighted cup as grip improves. The Silicone Training Cup is an open cup with a weighted base that resists tipping and a translucent body, so your baby can watch the water move and time the sip.
- Add a lid for out of the house. The 5oz Training Cup with Lid + Straw gives spill-resistant straw drinking in the stroller and the car with the lid on, and works as an open cup with the lid off at the table.
Pour an ounce or less and refill. More small pours beat one big one, every time. For how the cup types compare, see the sippy vs straw vs open cup guide.
What not to put in the cup
- Do not dilute formula. Mix it exactly as the container says. Extra water carries the same dilution risk as giving water directly.
- Skip juice in the first year. Common pediatric guidance is no juice before 12 months, and only small amounts after that.
- No cow’s milk as a drink before 12 months. It does not carry the right balance of iron and nutrients for a baby. When the time comes, our whole milk transition guide walks through the switch.
When to call your pediatrician
Call if you see signs of dehydration: noticeably fewer wet diapers than usual, a dry mouth, no tears when crying, or unusual sleepiness or floppiness. Call too if your baby has been given a significant amount of water before 6 months, or if you are ever unsure how much is safe. This guide is general information and does not replace advice from the clinician who knows your baby.
Questions parents ask
When can babies drink water?
Around 6 months, when solids start. Before that, breast milk or formula supplies all the fluid a baby needs, and general pediatric guidance is to skip plain water entirely. From 6 months you can offer small amounts with meals, and from 12 months water becomes an everyday drink.
Why can babies not have water before 6 months?
Two reasons. A young baby’s kidneys cannot clear extra water well, so too much can dilute the sodium in their blood, a rare but serious problem sometimes called water intoxication. And a newborn stomach is tiny, so water that goes in displaces the breast milk or formula that carries the calories and nutrients they actually need.
Can a 4 month old have water?
No, not as a drink. At 4 months breast milk or formula still covers hydration completely, including in hot weather. If your baby seems thirsty on a hot day, the usual advice is to offer milk feeds more often rather than water. Ask your pediatrician before offering water earlier than 6 months for any reason.
How much water should a 6 month old drink?
Small amounts. The American Academy of Pediatrics describes about 4 to 8 ounces a day from around 6 months until the first birthday, offered in a cup at mealtimes. At this stage the water is mostly cup practice: breast milk or formula is still the main drink and stays that way through the first year.
How much water should a 1 year old drink?
From 12 months water can be offered freely with meals and snacks. The American Academy of Pediatrics describes about 4 cups of fluids a day for ages 1 to 3, counting water and milk together, and more when it is hot or your toddler is active. Water and milk are the two drinks pediatricians generally recommend at this age.
Does a baby need water in hot weather?
Under 6 months, no. The standard advice for a hot day is more frequent breast milk or formula feeds, not water. Over 6 months, offer water with meals as usual and a little extra when it is hot, while milk feeds continue. If you see fewer wet diapers, a dry mouth, or unusual sleepiness, call your pediatrician.
Can I add water to formula to make it last longer?
No. Formula must be mixed exactly to the instructions on the container. Extra water dilutes the nutrition and carries the same risk of diluting the sodium in a baby’s blood. If cost is a strain, your pediatrician or a WIC office can point you to help.
What cup should I use to give my baby water?
A small open cup or a straw cup, both from around 6 months. An open cup builds the lip and tongue control that mature drinking uses, and a straw cup covers the stroller and the car. A 2oz first cup keeps early pours tiny, which is the difference between a wipe and a mop.
Should babies drink tap water or bottled water?
Most families can use tap water, and in many areas the fluoride in it is considered a benefit for developing teeth. If you use well water, or you are unsure about your local supply, ask your pediatrician or your local health department. Follow current guidance on preparing formula, which may differ.
The gear in this guide
Where these facts came from
- Babies can be introduced to water at around 6 months and need only about 4 to 8 ounces a day until they are a year old, because the rest of their liquid comes from breast milk or formula.healthychildren.orgthe awarding bodyread September 9, 2026
- Children aged 1 to 3 need about 4 cups of fluids a day, counting water and milk together, adjusted for activity and heat.healthychildren.orgthe awarding bodyread September 9, 2026