Your baby is starting solids, there’s a cup on the high chair tray, and you’re getting different answers from everyone. One site says a few sips, another says a whole cup, and a relative says babies have always had water. If you’re asking when can babies drink water, the official answer is clear: around 6 months, in small amounts, with breast milk or formula still the main drink. Below is a simple by-age table based on AAP and CDC guidance, how to get started, and when to call your pediatrician.
Quick answer: when can babies drink water?
- Under 6 months: healthy babies don’t need water. Breast milk, formula or both give them all the fluid they need (AAP).
- Around 6 months: you can start offering a little water. The CDC and AAP suggest 4 to 8 ounces (half a cup to 1 cup) a day in total.
- 12 to 24 months: the AAP suggests 8 to 32 ounces (1 to 4 cups) of water a day, alongside about 16 ounces (2 cups) of whole milk.
- Offer water in an open, sippy or straw cup. The AAP says this helps your baby build cup-drinking skills.
- Never add extra water to formula. The AAP warns that extra water can upset the balance of minerals like sodium and lead to serious problems, including seizures.
- Babies under 1 year shouldn’t drink juice (AAP).
Why babies under 6 months don’t need water
The AAP says babies in the first 6 months after birth do not need water or other liquids such as juice. Breast milk and formula already contain the water a baby needs, plus the nutrients that water can’t give.
The AAP also explains why extra water matters at this age: it disturbs the balance of electrolytes and minerals such as calcium, sodium and potassium, and this can lead to major health problems, including seizures. Adding extra water to formula also reduces the nutrients your baby gets. So always mix formula exactly as the label says.
A note for UK parents: the NHS says breastfed babies don’t need water until they start solids, and that formula-fed babies may be given small sips of cooled boiled water in hot weather. In the US, ask your pediatrician before offering any water to a baby under 6 months.
Water for babies by age: a simple table
| Age | Water | Main drink | Juice | Cup |
|---|---|---|---|---|
| 0 to 6 months | Not needed (AAP) | Breast milk and/or formula | None | Not needed yet |
| 6 to 12 months | 4 to 8 oz (0.5 to 1 cup) a day in total (CDC, AAP) | Breast milk and/or formula. No cow’s milk as a drink yet | None (AAP) | Open, sippy or straw cup |
| 12 to 24 months | 8 to 32 oz (1 to 4 cups) a day (AAP) | About 16 oz (2 cups) of whole milk a day (AAP), plus water | Whole fruit is preferred over juice (AAP) | Cup |
These amounts are for the whole day, not per serving. Your baby’s needs can vary, so use the table as a guide and ask your pediatrician if you’re unsure.
How to start offering water: 5 simple steps
- Wait for about 6 months. Most babies start water around the same time as solid foods. See our guide to signs your baby is ready for solids.
- Offer it at mealtimes. A few sips with solid food is a natural start. Keep breast milk or formula as your baby’s main drink.
- Use a cup. The AAP suggests an open, sippy or straw cup. The NHS adds that an open cup or a free-flow cup without a valve helps babies learn to sip and is better for their teeth.
- Keep it small. Stay within about 4 to 8 ounces for the whole day until 12 months. A lot of it will end up on the bib at first, and that’s fine.
- Keep it plain. Water, breast milk and formula are the drinks for this age. Skip juice and other sweet drinks.
For a full plan for the first months of solids, read introducing solid foods month by month and our baby feeding schedule.
Tap water, bottled water and boiling
In the UK, the NHS says drinking water for babies over 6 months does not need to be boiled first. In the US, the AAP and CDC guidance we used does not give one simple rule for every home, because water supplies differ.
- If you use well water, or you’re not sure about your tap water, ask your pediatrician or local health department whether it’s suitable for your baby.
- Mixing formula is a separate question. Follow the formula label and your pediatrician’s advice for the water you use.
What about juice?
The AAP says infants younger than 1 year should not drink juice, and that eating fruit is always preferred to drinking juice. The NHS says babies under 12 months don’t need fruit juice or smoothies. Water and milk are enough.
Related: toddler won't drink milk: what to offer after the first birthday.
When to talk to your doctor
Talk to your pediatrician if:
- you’re thinking of giving water to a baby under 6 months for any reason, such as hot weather or constipation;
- your baby is having fewer wet diapers than usual, or shows other signs of dehydration;
- your baby has vomiting or diarrhea and you’re not sure what to offer;
- your baby is drinking much less breast milk or formula than usual;
- you’re unsure whether your home’s water is suitable for your baby.
Get emergency help right away (call 911) if a young baby has had a lot of water and is unusually sleepy or irritable, looks puffy or swollen, or has a seizure. The CDC describes these as signs of water intoxication in infants. In the UK, call 999 in an emergency or NHS 111 for advice.
Frequently asked questions
How much water should a 6-month-old drink?
The CDC and AAP suggest 4 to 8 ounces a day in total for babies aged 6 to 12 months. Many babies take only a few sips at first, and that’s okay. Breast milk or formula still provides most of their fluid.
Can I give my 4-month-old water when it’s hot?
Ask your pediatrician first. The AAP says babies under 6 months don’t need water. In the UK, the NHS says formula-fed babies may have small sips of cooled boiled water in hot weather, and breastfed babies don’t need water before solids. For tips on keeping a baby comfortable in the heat, see heat rash in babies.
Can I give my baby water instead of a milk feed?
No. Until 12 months, breast milk or formula stays the main drink. Water is a small extra that helps your baby practice with a cup.
Sippy cup, straw cup or open cup?
All three are fine, according to the AAP. The NHS prefers an open cup or a free-flow cup without a valve, because it helps babies learn to sip and is better for their teeth.
When can babies have cow’s milk?
From 12 months. The CDC says that once your child is 12 months old, you can begin offering plain, pasteurized whole cow’s milk. Before then, breast milk or formula is the milk to use.
Find more feeding guides on our baby feeding page.
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Sources
- HealthyChildren.org (AAP): Recommended Drinks for Children Age 5 and Younger
- HealthyChildren.org (AAP): How to Safely Prepare Baby Formula With Water
- CDC: Foods and Drinks to Encourage
- CDC (MMWR): Hyponatremic Seizures Among Infants Fed With Commercial Bottled Drinking Water
- NHS: Drinks and Cups for Babies and Young Children
This article is for general information only and is not a substitute for medical advice. If you’re worried about your baby, call your pediatrician, or 911 in an emergency.