Dehydration is a significant health issue in children and can occur frequently as a result of hot and dry temperatures, intense physical playground activity and a lack of fluid intake.

How it can affect your child

Studies have shown that children are often arriving at school with a hydration deficit and not drinking enough fluid throughout the day to maintain adequate hydration (1).

This can affect their performance and lead to:

  • Lower cognitive and physical performance
  • Increased feelings of aggression and irritation

Mild dehydration (2-3% body weight loss through sweat) can significantly impair your child’s concentration at school and impact the following:

  • Short term and long term memory and retrieval
  • Attention span and alertness span
  • Language skills (both written and verbal)

Research has found that hydrated students often perform better on verbal tasks, compared to children that were dehydrated (2).

Factors that affect how much your child sweats

Children can sweat up to 400 ml per hour, making them prone to a hydration deficit.

Furthermore, children’s thermoregulatory systems are less effective than adults, meaning that dehydration is accompanied by a faster core temperature increase compared to adults (3).

The following factors can also affect your child’s hydration status:

  • Type and intensity of sport – sport affects the amount of heat the body produces and consequently the core temperature and fluid loss through sweat.
  • Body size – children have a smaller mass to surface area ratio and therefore lose fluid through sweat more rapidly than adults. This puts them at a higher risk of dehydration (4).
  • Clothing – the type of clothing affects the quantity of sweat produced and evaporative capacity.
  • Environmental conditions – hot and humid weather increases sweat rates.
  • Heat acclimatisation and fitness level – at the start of the school year or sporting season when children have a sudden increase in activity levels, they may be at particular risk of dehydration due to a lack of acclimatization (5).

How much fluid does your child need? (6)

  • Children 1-3 years – require 1 litre
  • Children 4-8 years – require 1.2 litres
  • Girls 9-13 years – require 1.4 litres
  • Boys 9-13 years – require 1.6 litres
  • Girls 14-18 years – require 1.6 litres
  • Boys 14-18 years – require 1.9 litres

Kids and thirst

Don’t rely on your child to realise they’re thirsty – they may not!

Children may be at risk of dehydration because they don’t often respond to the early stages of thirst.

During exercise, kids (compared to adults) may not recognise the need to replace lost fluids and are less likely to drink according to thirst.

Top tips for staying hydrated

  • Ensure children are offered regular access to fresh clean water.
  • Children are more likely to drink water when it is chilled – freeze the bottom quarter of you child’s water bottle overnight and fill before school
  • Keep children cool and in the shade as much as possible

On hot days

  • Avoid giving your child any sugary drinks/ice blocks.
  • Pack Hydralyte mini bottles in your child’s lunchbox, or have another small water bottle half frozen in the lunch box.
  • Pick up children from school with Hydralyte ice blocks to have in the car on the way home to cool them down.

Do your kids come home with an empty drink bottle from school? Are they getting enough fluid during the day? 

Image courtesy of Shutterstock.com
(1) Gibson-Moore, H. (2013) ‘Improving hydration in children: A sensible guide’ Nutrition Bulletin
(2) Anci, K. Constant, F. Rosenberg, I. (2006) ‘Hydration and Cognitive Function in Children’ Nutrition in Clinical Care Vol 1 (October) pp. 457-464
(3) Department of Health and Ageing, National Health and Medical Research Council. Nutrient Reference Values for Australia and New Zealand. Including Recommended Dietary Intakes. Canberra: Commonwealth of Australia; 2006.
(4) Bar-Or, O. Wilk, B. (1996) ‘Water and Electrolyte Replenishment in the Exercising Child’ International Journal of Sports Nutrition Vol. 6 pp. 93-99
(5) Medscape Reference [Internet]. Pediatric Dehydration. 2013. [cited 2013 July 29]. Available from: http://emedicine.medscape.com/article/801012-overview
(6) Anci, K. Constant, F. Rosenberg, I. (2006) ‘Hydration and Cognitive Function in Children’ Nutrition in Clinical Care Vol 1 (October) pp. 457-464
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  • A very informative and helpful read.


  • Great tips and love the references at the end. A great article to keep families aware


  • My kids always drank lots of water. Whenever we went out, no matter where, they always made sure to take a bottle of water. Now my grandkids do the same


  • Summer is here again… Such a wonderful read.


  • My kids drink bottles usually came home empty, depending on the weather and the activity levels that particular day. My daughter still carries a water bottle around with her, everywhere she goes


  • Being a Mum of 5 children, I’m very lucky that they drink plenty of water. They prefer water rather than any other drink. I think that it’s because I have taught them from the youngest age possible that it is very healthy for you, if you drink lots of water …. just like I do.


  • Water was and is the first offer of drink to my children. It is also an example that we as parents need to set. We all drink water with our meals and very rarely drink any type of sugary drink.
    Now both my girls are in their late teens and drink mostly water still.


  • My 2 year old loves water. That’s pretty much all she drinks and would easily drink over a litre a day. She has the occasional baby Cino or glass of milk otherwise it’s just water. I’m very lucky


  • I also found out from my dentist this week that not drinking enough water is a cause of bad breath, something my younger daughter has. Another good reason to drink more water!


  • I think we sometimes forget how active our little ones can get and how quickly dehydration can occur. Good habits re enough water / liquids need to be introduced and formed young. Know that I myself find it hard to make sure I drink enough water rather than just reaching for an unhealthy or sugary option.


  • sounds awesome and looks great


  • Good to know especially the amounts suggested per age. Thanks!


  • I found this very informative and my mind wandered to when I was a child.. I remembered a special day when we marched around a sporting field then had to stand in the blazing sun for ages..no hats no water..thank heavens schools are now better educated.


  • Some really important information and tip – thank you so much!


  • We always have a drink bottle in reach and encourage water at meal times. Some days it is easier than others to get the water in.


  • Great information, my girl is finally taking this on board and is more regularly coming home with an empty drink bottle. We got her an insulated thermos type one this year and the nice icy cold water is definitely making a difference.


  • This is so informative! Thank you!!


  • This is an ongoing discussion we have with our son to teach him about hydration. It works great some days, and not so great on others. Thankfully, he brings his water bottle home empty, sometimes refills it at school. We also have water with dinner.


  • Headaches are a good indication.My son spent time swimming this week and came home headachy and sun burnt. Grrr.


  • Great read & fluids Re most important, I’ve also heard coconut water has an extra 30%, am very keen to learn more as my children are very active


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