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When is it safe to give my baby water?

Have you ever had a well-meaning family member tell you to boil some water and offer it to your baby? Or that you were perfectly fine when offered it as a baby?

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It seems logical to offer water to your baby for additional hydration, especially on those hot days, but did you know that providing water to a baby under six months of age is not recommended? There can be several consequences if your baby is given water. In this article, we are going to explore why.

Your baby’s kidneys are small and underdeveloped compared to an older child and adult. Their tiny tummies can also only hold a certain amount of fluid. Drinking water on its own can put them at risk of water intoxication and reduce the amount of essential nutrients they receive from breast milk or formula. Let’s explore this a little further.

Nutritional Importance

It is no secret that your baby will develop quite rapidly during the first few years of their life. There is so much brain development occurring and maturing of internal organs, so it is essential that your baby receives optimal nutrition for this growth and development.

Babies have a tiny stomach; at one month of age, your baby’s stomach is the size of an egg, holding a capacity of 80-120ml. Digestion is fast, and your baby will require multiple feeds daily to meet their growing demands. When a baby under six months is offered water, it fills up their stomach, leaving no room for the nutrient-rich milk (breastmilk or formula), which provides all the essential vitamins, minerals, fats, and hydration your baby requires.

The World Health Organization states that babies under six months of age do not require water and that the only fluid required is breastmilk or formula for nutrition and hydration.

Water Intoxication

Water can be very toxic to a baby if given in even moderate quantities and in a short time. Yes, water can be harmful to your baby. You read that right. As mentioned above, your baby is rapidly growing; however, their little organs are pretty immature, and as a result, if a baby is given water under six months of age, it can cause serious problems.

The kidneys are designed to filter waste products from your body by removing the waste from the blood and returning cleaned blood to the body. As well as acting as a filter, the kidneys help control blood pressure, remove fluid from the body to maintain correct levels for optimal functioning and maintain the chemistry levels (salt, etc.) within the body.

When a baby receives too much water, the kidneys cannot maintain their role in processing the fluid. As a result, fluid build-up occurs, causing too much water to transfer into the bloodstream. When this happens, the blood can become too dilute, causing severe electrolyte disturbances, particularly the salt concentration in the body becoming too dilute, which can cause brain swelling.

Signs to look out for

The signs of water toxicity are essential for any parent, no matter the age of your baby/child. Signs include.

  • Lethargy

  • Vomiting

  • Seizures

  • Drowsiness

  • Inconsolable crying

In cases where brain swelling occurs, there is always the risk of brain damage, which is why it is so important to remain vigilant and educate anyone in direct contact and care with your baby.

If you are concerned about your baby or have begun to display water toxicity signs, please consult a healthcare professional immediately.

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Current recommendations in Australia are

  • For babies under six months of age, only offer breastmilk and formula, this provides babies with the nutrients and hydration.

  • During hot days, continue to offer milky feeds only and offer more frequently. Your baby may also demand more feeds during this time.

  • Once your baby reaches six months, you can introduce small amounts of cooled boiled water. This aims to get them used to the taste and develop healthy habits.

  • To avoid water toxicity, babies over six months should only be given 120-250ml (4-8 oz) of cooled boiled water daily. Continue to offer breastmilk or formula feeds as the primary drink source.

  • If formula feeding, always follow the tin instructions and do not add additional water to bottles, as this can lead to water toxicity.

  • After 12 months, your baby can be encouraged to drink more water (1-4 cups per day). Tap water can also be offered without boiling it.

For more information on this topic, see the below links.

My name is Vanessa Barnard, and I am the founder of Illoura Birth. I am a Childbirth and Newborn Educator, Doula and Paediatric Nurse. My mission is to support families on the journey to meeting their babies and thereafter with holistic and evidence-based information. My focus is to inspire and boost your confidence on this journey through pregnancy, birth & postpartum. 

Resources & further reading

The Royal Children’s Hospital – Parent information:



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