When Can Babies Drink Water Safely
The short answer
Babies under 6 months should NOT be given water. Breast milk or formula provides all the hydration they need, even in hot weather. Giving water to a young baby can cause water intoxication, a dangerous condition where sodium levels drop to dangerous levels, potentially causing seizures. After 6 months, when solids begin, small sips of water (2-4 oz per day) can be offered in a cup. By 12 months, water becomes a regular part of the diet alongside whole milk.
By Age
What to expect by age
Do not give water to babies under 6 months. Their kidneys are immature and cannot process extra water efficiently. Even small amounts of water can dilute the sodium in their blood to dangerous levels (hyponatremia), which can cause seizures, brain swelling, and in severe cases, death. Breast milk is 87% water and provides all the hydration your baby needs. Formula already contains the correct amount of water when mixed according to directions. In hot weather, offer more frequent breast or formula feeds rather than water.
Once your baby starts eating solid foods, you can begin offering small amounts of water - about 2-4 oz per day from an open cup or straw cup. This helps your baby learn to drink from a cup and provides a small amount of additional hydration to help with the transition to solids. Water at this age is for practice, not primary hydration - breast milk or formula remains the main fluid. You do not need to worry if your baby only takes a few sips.
You can gradually increase water offered at mealtimes. Aim for about 4-8 oz per day total. Continue breast milk or formula as the primary beverage. Water should be offered in a cup, not a bottle, as this supports oral motor development and helps with the eventual transition away from bottles. If you live in an area with fluoridated tap water, this also provides dental benefits.
After 12 months, water becomes a regular drink alongside whole milk. Toddlers generally need about 1-4 cups of water per day depending on activity, climate, and how much water-rich food they eat. Avoid juice and sugary drinks - water and milk are the best beverages for toddlers. If your toddler is drinking so much water that it replaces milk and food, or seems excessively thirsty, mention it to your pediatrician as this can occasionally indicate a medical condition.
What Should You Do?
When to take action
- Your baby under 6 months is getting all fluids from breast milk or formula with no water supplements
- Your 6-12 month old takes a few sips of water at mealtimes and still drinks breast milk or formula as their main fluid
- Your toddler drinks water throughout the day and has pale yellow urine, indicating good hydration
- You are unsure about how much water to offer at different ages
- Your baby seems excessively thirsty and drinks much more water than expected for their age
- You are concerned about constipation and wondering if more water would help
- Your baby under 6 months has accidentally been given a significant amount of water and is showing symptoms like lethargy, irritability, swelling, or seizure-like activity - seek emergency care
- Your child is showing signs of dehydration (no wet diapers for 8+ hours, no tears, dry mouth, sunken fontanelle) and is unable to keep fluids down
Sources
Related Resources
Related Feeding Concerns
Is My Baby Dehydrated?
Dehydration in babies happens when they lose more fluids than they take in, usually from vomiting, diarrhea, fever, or inadequate feeding. Key signs include fewer than six wet diapers in 24 hours, no tears when crying, a dry mouth, sunken fontanelle (soft spot), and unusual drowsiness. Mild dehydration can often be managed at home with extra fluids, but moderate to severe dehydration requires prompt medical attention.
Baby Not Drinking Enough Milk
Babies naturally vary how much milk they drink from day to day, and a temporary dip in intake is usually nothing to worry about. Common causes include growth pattern changes, distractibility, teething, mild illness, or simply not being as hungry on a particular day. As long as your baby is having plenty of wet diapers and continuing to gain weight along their growth curve, they are likely getting enough.
Introducing Cow's Milk at 12 Months
Whole cow's milk can be introduced starting at 12 months of age. Before 12 months, cow's milk does not have the right balance of nutrients for babies and can strain immature kidneys. When your baby turns one, you can offer whole milk (not reduced-fat) as a drink alongside meals. Some babies love it immediately, while others need time to adjust to the different taste. A gradual transition by mixing formula or breast milk with cow's milk over a week or two often helps.
When to Introduce Allergens to Baby
Current guidelines recommend introducing common allergens (peanut, egg, cow's milk products, tree nuts, wheat, soy, fish, shellfish, sesame) starting around 4-6 months when your baby is developmentally ready for solids. The landmark LEAP study showed that early introduction of peanuts (by 4-6 months) reduced peanut allergy risk by 80% in high-risk infants. Do not delay allergens - the old advice to wait until 1-3 years has been reversed because early exposure actually prevents allergies.
I'm Worried My Baby Is Aspirating During Feeds
Aspiration means liquid or food enters the airway instead of the stomach. Occasional coughing during feeds is common and does not usually indicate aspiration. True aspiration is less common and may present as recurrent respiratory infections, a wet or gurgly voice after feeds, or chronic cough. If you are concerned, a swallow study can provide a definitive answer.
Baby Biting Nipple While Nursing
Biting during breastfeeding is a common challenge, especially when babies start teething. It can be startling and painful, but it is almost always a phase that can be managed. Babies cannot actively nurse and bite at the same time because their tongue covers the lower teeth during proper sucking. Biting typically happens at the beginning or end of a feed when the latch is not active. With some gentle strategies, most babies learn quickly that biting ends the feeding session.