Why can't babies have water?

A guide for parents

February 01 2019

Why can't babies have water?

If you give a baby younger than 6 months old too much water, there can be serious health implications. Water can interfere with your baby's natural ability to absorb the nutrients in breastmilk or formula feeds. It can also cause the tummy to feel full, so they won't feed on breastmilk or formula. This could even be fatal.

There’s lots of misleading information out there over what babies can and can't drink, and water consumption has many strict rules. Let’s take a look at the facts.

What happens if babies have water?

Giving your baby additional water can disrupt your baby's electrolyte balance, which can cause seizures, brain damage and even death. Diluting formula with water can lead to a dangerous condition called water intoxication. This can affect baby's growth and development and make them very sick.

When can babies have water?

Before the age of 6 months, baby's kidneys are too immature to correctly filter plain water. At 6 months you can start to introduce small amounts of additional water, but this should not replace breastfeeding or formula intake. From 6-12 months it’s more about practicing with a sippy cup and getting bub used to the taste of water.

What if it is hot and my baby is thirsty?

It may be tempting to offer bub small amounts of water on a hot day, but it isn’t necessary. Breastmilk is made up of around 80% water and you’ll find your baby will opt for more feeds on a hot day. Formula-fed babies can have small amounts of water on a hot day if they are thirstier than usual. If your child is under 6 months it’s important to give boiled tap water, but allow it to cool first before offering. Many parents ask, 'why can't my baby drink beast milk and water?' but there really is no need to double up. 

getty images

getty images

What do you do if your baby has drunk water?

A small amount of water as a one-off won’t harm bub, but monitor for any changes to behaviour. Large doses of water can lead to water intoxication and early symptoms of this are subtle, therefore it may not be until a seizure hits that you realise your child is in danger. In this case, parents should seek urgent medical attention.

Is tap water bad for babies?

After the 6 month mark, babies can start to have small cups of water straight from the tap. Before this age, freshly boiled water - cooled - is best practice because boiling the water kills any bacteria in it.

Guidelines around newborn and infant feeding have changed over the years so it’s important to have these discussions with grandparents, new carers or anyone who may be wondering if babies drink water or just milk. These answers can be surprising to many, even to those who have had children!