When Can Babies Have Water? A Guide for Parents
It seems like the most harmless thing in the world — a few sips of water on a hot day. But for a young baby, plain water can actually be dangerous, and the timing of when to introduce it matters more than most parents realize. The short version: babies under 6 months don't need water and shouldn't be given it (outside of properly prepared formula), small amounts are fine from around 6 months with solids, and water can flow freely after the first birthday. Here's the full picture, and the important safety reasons behind it.
0–6 Months: No Water Needed
For roughly the first six months of life, your baby does not need water. Breast milk and correctly prepared formula are predominantly water and provide all the hydration a young baby requires, even in warm weather. (Worried about hydration? Here's how to tell if your baby is getting enough milk.)
Why is plain water actually dangerous for young infants?
- Risk of water intoxication. A young baby's kidneys are immature and can't process a large water load. Extra water dilutes the sodium and other electrolytes in their bloodstream, which can cause a serious condition called hyponatremia (water intoxication). Symptoms include unusual fussiness or drowsiness, low body temperature, facial puffiness, twitching, and in severe cases seizures. It's rare, but it's serious — and it's entirely avoidable.
- It crowds out nutrition. A baby's stomach is tiny. Filling it with calorie-free, nutrient-free water means less room for the breast milk or formula that fuels their growth, which can lead to poor weight gain.
Important exceptions and cautions
- Formula must be mixed exactly as directed. Never over-dilute formula to "stretch" it or add extra water — that carries the same water-intoxication risk. Always follow the ratio on the tin. For more, see our formula feeding guide.
- Hot weather and illness. Even when it's sweltering or your baby is unwell, the answer for under-6-month-olds is more frequent milk feeds, not water. If you're worried about dehydration during heat or a fever, call your pediatrician rather than offering water on your own.
6–12 Months: A Little Water Is Okay
Once you begin introducing solid foods around 6 months, you can start offering small amounts of water. (Not sure your baby is ready for solids? Take our free solids readiness quiz.)
- How much. A few sips — roughly 1–2 oz (30–60 ml) — with meals is plenty at this stage. There's no need to push it.
- The purpose. Water at this age is about learning the skill of drinking from a cup and helping wash down solids — not hydration. Breast milk or formula remains the main source of fluids and nutrition through the first year.
- How to offer it. Use an open cup, a straw cup, or a sippy cup with meals. Open-cup and straw practice supports oral-motor and speech development, so they're worth introducing early.
- Skip the juice. Pediatric guidance recommends no fruit juice before 12 months. It offers no benefit over whole fruit and adds unnecessary sugar.
Wondering how water fits alongside milk and solids day to day? Our baby feeding schedule by age shows how it all comes together.
12+ Months: Water Is Welcome
After the first birthday, water can be offered freely between meals and snacks, and it becomes an everyday drink alongside whole cow's milk (or an appropriate alternative). Around this age, many families are also thinking about weaning from breastfeeding or adjusting formula routines. A general starting point many pediatric sources suggest is roughly a cup of water per day for each year of age (so about 1–4 cups for a 1-year-old, adjusted for activity, weather, and appetite) — but let thirst and your child's cues guide you, and check with your pediatrician if you're unsure.
Cups and Water: A Quick Progression
- 6–9 months: Introduce an open cup (held by you) and a straw cup at mealtimes for practice.
- 9–12 months: Your baby gets more skilled; keep offering small sips with meals.
- 12+ months: Water in an open or straw cup throughout the day. Many experts suggest moving away from bottles around this age.
A note on the water itself: safe tap water is generally fine, and in many areas it provides fluoride that supports dental health. If you use well water or have any concerns about your local water supply, ask your pediatrician about what's best for your baby.
Frequently Asked Questions
My baby is constipated — can water help? For babies already on solids (6+ months), small amounts of water can help, and so can certain fruits. For younger babies, talk to your pediatrician before offering anything other than milk.
Can I give my under-6-month-old water in very hot weather? No — offer more frequent milk feeds instead, and call your doctor if you're worried about dehydration. Their milk provides all the fluid they need.
What are the signs my baby is dehydrated? Fewer wet diapers than usual, a dry mouth, no tears when crying, a sunken soft spot, and unusual sleepiness. If you see these, contact your pediatrician promptly.
When to Talk to Your Pediatrician
Call your pediatrician right away if your young infant has been given a significant amount of plain water, or if you notice signs of dehydration (fewer wet diapers, a sunken soft spot, unusual sleepiness) or possible water intoxication (unusual fussiness, drowsiness, twitching, puffiness, or seizures — the last is an emergency). Also check in whenever you're unsure about fluids for your baby's age and situation, especially in hot weather or during illness. When it comes to your baby's hydration, there's no such thing as a silly question.
Log It: When you start offering water with meals, note it alongside a feeding entry in MyBabyTracker to keep a complete record of your baby's intake — and share it with a caregiver so everyone's consistent. Create a free account to start tracking feeds.
This article is for informational purposes only and is not a substitute for professional medical advice.