The short answer
A baby under 6 months who is exclusively breastfed does not routinely need water, even in hot weather; offer the breast more often instead. For a baby who drinks formula, use water only in the exact amount needed to prepare it according to the product instructions. Do not dilute formula or give extra water routinely. If your baby is vomiting, has diarrhea, or is urinating less, seek advice rather than treating the problem with water at home.
In this guide · 10 sections
Keep in mind
- Breast milk provides the water a baby needs during the first 6 months; in hot weather, offer feeds more often rather than extra water.
- Water used to prepare formula is not the same as giving a baby a drink; never change the water-to-powder ratio.
- Do not use water, sugar water, herbal tea, or juice for hiccups, suspected dry mouth, or fussiness.
Why does a breastfed baby not need water?
Breast milk is mostly water and changes to meet a baby’s fluid and nutrition needs. The WHO advises offering more breastfeeds, rather than water, to babies under 6 months, even on hot days.
A baby who wants to feed again soon may be responding to warmth, cluster feeding, or a need for closeness. Do not assume this alone means dehydration or low milk supply; swallowing, diapers, weight monitoring, and overall wellbeing give more context.
How is water used for a formula-fed baby?
Use water only to prepare formula, with the exact water-to-powder ratio given by the manufacturer. Adding extra water does not make formula safer. It can mean your baby gets too little nutrition and can disturb the body’s salt balance. Using less water is not safe either.
Advice about preparing formula and water safety can differ by country, water source, and product instructions. Follow the label and the advice of your baby’s healthcare team; also follow the label when deciding whether prepared formula can be kept.
What can you do in hot weather?
Avoid overdressing your baby, keep the room comfortably cool, and offer the breast more often if your baby is breastfed. If your baby drinks formula, offer the usual correctly prepared feeds in response to their cues; do not add water to the bottle.
A marked decrease in wet diapers, dry mouth, fewer tears, difficulty waking, or unusual sleepiness should not be put down to hot weather alone. If these happen with vomiting or diarrhea, seek healthcare advice promptly.
What should you avoid for hiccups or fussiness?
Do not give water, sugar water, herbal tea, or fruit juice to stop hiccups, ease gas, or settle a baby under 6 months. These can replace breast milk or formula, and some products may not be suitable for babies.
Hiccups often stop on their own. If your baby seems uncomfortable after a feed, holding them upright calmly and burping them if needed may help. Seek assessment if they have repeated coughing, turn blue, or cannot feed.
Do vitamins, medicines, or oral rehydration solution count as water?
A vitamin or medicine drop recommended by a doctor is not the same as routinely giving water and should be used at the recommended dose. Oral rehydration solution is also different from plain water; during vomiting or diarrhea, give it only if a healthcare professional advises that it is suitable for your baby’s age and situation.
Do not prepare a salt-and-sugar mixture at home, dilute formula, or try to replace fluid loss with plain water. Fluid loss can worsen quickly in a newborn.
How can you tell whether your baby is getting enough fluid?
Do not judge by one diaper alone. Consider the pattern of wet diapers expected for your baby’s age, effective swallowing, feeding frequency, weight checks, and alertness when awake. Diaper expectations change quickly in the first days, so ask your healthcare team what is expected at your baby’s age.
If your baby is feeding well, has their usual diapers, and seems well, hot weather alone is not a reason to add water. If you are worried, sharing the last 24 hours of feeds and diapers can help with assessment.
What can you do today?
In hot weather, dress your baby in light layers and offer the breast more often if they are exclusively breastfed.
When preparing formula, follow the exact water and powder measurements on the container; do not add water to the bottle afterwards.
Note feeds and wet diapers over the last 24 hours. If they decrease noticeably, seek healthcare advice instead of offering water.
When to seek support
Some signs need emergency help; other concerns can be discussed with your child’s healthcare team.
- A marked decrease in wet diapers, dry mouth, fewer tears, a sunken-looking soft spot, or increasing sleepiness.
- Your baby refuses feeds, cannot swallow effectively, vomits repeatedly, or has diarrhea.
- Difficulty waking, reduced responsiveness, blue color, or breathing difficulty; urgent assessment is needed.
Sources used for this guide
- World Health Organization (WHO) — Breastfeeding – Questions and Answers
- World Health Organization (WHO) — Breastfeeding
- World Health Organization (WHO) — Exclusively Breastfeed for 6 Months
- CDC — Infant Formula Preparation and Storage
English editorial review:
The English text and regional guidance have been checked editorially. This is not an individual clinical assessment.
Luluna provides general parenting information. It does not diagnose conditions or replace your child’s healthcare professional.
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