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Does my little pumpling need water in the heat?

An FAQ during the Summertime is often something along the lines of "Do I need to give baby water on days when it's hot?" It's a reasonable question and I understand why it's asked especially when exclusive pumping often gets mistaken for formula feeding when advice is given.

So if your exclusively pumping and in this case, not using formula, should you give your baby a bottle of water in a heatwave?

My short answer is no, your little pumpling does not need any extra water. Research has found that healthy breastfed babies do not need water supplementation in hot weather. Remember that pumping is breastfeeding, so this applies to exclusive pumping babies too!

Your Little Pumpling does not need to be given water in addition to breastmilk for many reasons.

Breastmilk is mainly water!

The first and most important reason that baby does not need water during hotter days is that breastmilk composition is majority water. The World Health Organisation and many other health resources explain that breastmilk consists of 80% water. This means that baby is receiving lots of liquid during a feed. Breastmilk provides enough water for a baby to remain hydrated during hot weather.

Babies feed more often

During warmer weather, you may find that your little pumpling wants the bottle more often than normal. You may also find that these more regular feeds are smaller than normal too. Baby will still tend to drink around the same amount in a 24 hour period. This behaviour is totally normal and mimics what a nursing baby would do too.

Responsive bottle feeding is best practise at all times but especially in the heat. Responsive bottle feeding means that you offer a bottle when baby shows signs of hunger rather than when they are 'scheduled' or 'due' to have a bottle. You are responding to their needs. Kellymom, a great breastfeeding resource has more information on infant hunger cues.

Tip: You can keep a bottle that has been drunk from for up to 1 hour - If your baby does not have any immune compromising conditions and is healthy. So if baby feeds a little and stops, offer it again near the end of that window to ensure no milk is wasted.

The Delicate Sodium Balance

Your baby's body is very carefully regulated and adding more water to their diet when it is not necessary can throw off their systems.

When you give baby more water than they need, their kidneys have to filter out the liquid that the body does not need. As their kidneys are immature they release sodium along with the excess water. This can reduce sodium levels, in severe cases, effecting brain function.

Geographical Differences

It's important to be grateful that in the UK our drinking water is very clean & safe for us to drink. However, when looking across cultures to different countries, giving water to baby could increase the likelihood of illness such as diarrhoea or vomiting. In places where the local water supply is not guaranteed to be clean or safe for consumption, babies can get sick from dirty water so it's best to not feed them any water if they are exclusively fed breastmilk.


There are plenty of reasons why your baby does not need extra water in a heatwave. The first being that breastmilk is majority water so baby is already consuming quite a lot of liquid and therefore will not be dehydrated. The second being that baby adjusts their feeding pattern to accommodate for the thirst that heat causes so they should not be thirsty and therefore water would not quench them. The third being that excess water can effect the equilibrium of a baby's body, one system effect is the urinary system aka the kidneys which filter blood and create urine. The excess water can mean a reduction in sodium and this has some life threatening symptoms if unnoticed. In some places, where water is not always safe to drink, it is strongly advised for babies to not be given water as dirty water can carry many diseases which cause diarrhoea and vomiting.

If your baby is healthy, exclusively fed breastmilk and is under 6 months. You do not need to give your baby additional water during a heatwave. Breastmilk provides everything a baby needs. Conduct responsive bottle feeding techniques which mean feeding baby whenever they show signs of hunger.

One fun way to keep babies fluids up is by making breastmilk popsicles! If you'd like to watch a video on how to make breastmilk popsicles, head over to the Little Pumpling Instagram.

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Enjoy the sunshine!



Please note:

If you offer a combination of formula and breastmilk, the rules are different as it depends on how much formula in a 24 hour period. It's important to talk to a health care professional before giving water.

If you're worried:

If you're worried about your baby and they're showing signs of dehydration, please contact your GP / Call 111 for advice.



Additional water is not needed for healthy breast‐fed babies in a hot climate by Ashraf et al, 1993.

Breastfeeding - WHO

Breastfeeding through hot weather

Dehydration in Children - NCT

Drinking water can be harmful to infants

Drinking-water quality, sanitisation and breastfeeding

Perceived Incentives & Barriers to exclusive breastfeeding

Water supplementation in exclusively breastfed infants during summer in the tropics by Sachdev et Al, 1991.

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