When should I give my baby water to drink?

by Dr Maraschin, expert paediatrician
Baby Yum Yum - When should I give my baby water to drink
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“Should I give my baby water?”, is a very important question. Water is an essential part of our health because our body uses water to regulate our temperatures, excrete toxins and it is, in fact, used in all our cells and tissues.

As adults we have been taught that we should be drinking about 2 litres of water per day to make sure our bodies can do all these wonderful things. Naturally, we want to do the very best for our babies so the question often arises as to when you can give a baby water to drink and how to introduce water to a baby.

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Let me show you a graphic – I like to see things in picture form and that makes it way more understandable.

the size of a baby's stomach in the first six months of its life

Image taken from https://deeprootsathome.com/is-your-newborn-getting-enough-milk/

You can see from this picture that your baby’s tummy is very tiny and doesn’t grow much in the first six months. This tiny tummy barely has space for milk, never mind anything else.

Should I give my baby water to drink? 

If you’re wondering how their tiny tummy will have space for water above their milk needs? The short answer is that “you shouldn’t”. A baby should not be given water to drink in the first six months of life – thereafter, they can have small sips of water.

Doesn’t my baby need to drink water to stay hydrated?

Mother Nature already took care of that problem. Breastmilk has all the water a baby needs in it. A mother’s milk can be divided into foremilk and hindmilk. Foremilk is predominantly water with a few nutrients. The foremilk is perfectly designed to contain just the right quantity of water to fully hydrate your baby.

If baby is formula fed then the water used to dissolve the formula will provide for all the baby’s hydration needs. It is really important that the formula is mixed correctly with the right volume of water to formula powder to ensure baby is getting all the nourishment it needs.

What will happen if I give a baby water to drink too soon

What will happen if I give a baby water to drink too soon?

Let’s go back to our picture to answer this question. A baby only has space for a little bit of liquid and that liquid needs to be nourishing. Water will fill that tiny space and leave no room for the vitamins, minerals, fats and proteins that are essential for a baby’s development.

A baby in the first six months of life gets everything that they need to grow from their milk so nothing should take up the space in their stomach that’s needed for milk. Doing so can have serious health implications. Moms may now ask why solids are often introduced from 17 weeks but the solids given at this stage are given in small quantities and do not take the place of milk.

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Why shouldn’t you give a baby water to drink? 

I am always reluctant to introduce concepts that can cause parents to panic but besides the tummy space and nutrition there are other reasons for avoiding water in very young babies. I am going to mention them because you can read about these concerns in the literature and most Paediatric Associations will warn you about these serious side effects, if you search for “when to introduce water to babies.”

Water intoxication

This sounds very counter intuitive. Water and toxin don’t sound like they should be used in the same sentence but as with anything else, “too much of a good thing is bad”.

A baby’s kidneys are little and are not developed well enough to cope with water as well as milk. When water is added to the diet too early this can be too much for the kidneys to excrete and the water finds its way into the bloodstream. This extra water dilutes the fluids in the blood and causes the sodium levels to drop. This condition is known as hyponatremia. The cells swell with water and once the cells of the brain swell the child may be in trouble.

Sign of water intoxication in babies

Watch out for vomiting, changes in behaviour, and dizziness. Obviously in a tiny baby you won’t know if the baby is dizzy but let’s say your baby accidently got a large gulp of bath water and then begins vomiting and behaving differently, then seek medical assistance.

Treatment of water intoxication

In mild cases water intoxication is treated by simply stopping the water intake. The kidneys will usually be able to excrete the unnecessary water.

In severe cases a doctor may need to treat with diuretics. This is a medicine which will help the body to excrete the excess water. The baby may also be given a saline solution to correct the sodium levels in the blood.

How to avoid water intoxication in babies

  • Follow the guidelines for introducing water.
  • Do not dilute breastmilk or formula with water
  • Watch your child closely when in the bath or pool so that baby doesn’t accidently swallow a lot of water.
  • Avoid giving your child cups or scoops in the bath until he or she is old enough to understand that drinking the bath water isn’t a great idea.

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Do I need to give my baby water to drink if they have gastroenteritis?

Bear in mind that the advice given here is for babies under the age of six months. Any baby with gastroenteritis in this age group should be under the care of a healthcare professional. You will be advised on how much rehydration solution to give while baby is ill. If your baby requires admission to hospital then a drip will be put up. The rate at which the drip runs controls how much fluid is being put into baby’s system. You definitely don’t need to concern yourself with intoxication under these circumstances.

In children older than six months it is usually recommended that they are given little sips of rehydration solution throughout the day. In total the baby will probably need about 50mls per loose stool or vomit. If baby is unable to tolerate the fluids and continues to vomit then admission to hospital is likely to replace fluids. Again, the rate at which baby is given fluids via the drip will be monitored.


In my experience parents have enough to worry about in the first couple of months of a baby’s life with 3-hourly feeds, nappy changes, tummy time and sleepless nights. “Should I give my baby water to drink” certainly doesn’t need to be added to this list. Thank goodness for this because baby doesn’t need water.

From six months of age baby may be introduced to water but this is mainly to get baby used to the taste. At this stage you would not give more than a few little sips at a time – teaspoon sizes. Any more than this will fill that little tummy. At about a year of age baby may have between 50 and 100mls of water spread throughout the day if baby is hot and thirsty.

After this age your child can have water freely and, in fact, we encourage it. A good amount of water in the diet helps with constipation and does wonders for the child’s overall health.




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