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At birth, a baby’s body consists of about 75% fluid. For older children and adults, about 60% of the body is fluid. Fluid is really important for health, as the cells in our bodies depend on it to function normally and also to get rid of waste products. Both the amount and type of fluids adults and children consume can have a significant impact on their health.

The amount a child needs to drink can vary greatly, depending on age and gender as well as weather and physical activity. The European Food Safety Authority (EFSA) has guidelines about how much fluid children need – these are summarised below. As a general rule of thumb, children aged 4 to 13 should aim to drink approximately 6-8 glasses of fluid a day, with younger children needing relatively smaller servings (e.g. 150ml glass for a 4-year-old and 250ml for an older child).

How much water should you drink a day?

  • Boys and girls aged 4-8 years need 1.1 to 1.3 litres per day
  • Girls aged 9-13 years need 1.3 to 1.5 litres per day.
  • Boys aged 9-13 years need 1.5 to 1.7 litres per day.

In addition to the fluid we get from drinks, many foods also contain water, and so foods with a high water content can also top up our fluids. Fruit and vegetables in particular can have a high proportion of water – for example, cucumber and watermelon are over 90% water!

What are the signs of dehydration in children?

Hydration is particularly important for children as they have higher water requirements in relation to their body weight than adults. Infants and young children, in particular, are also less heat-tolerant and so drinking small amounts often is essential, particularly in hot weather, or when they are very active and fluid losses are higher. As children don’t always recognise the early stages of thirst, they are at risk of becoming dehydrated. Even mild dehydration can make children irritable, and can cause tiredness, headaches, lack of concentration, reduced mental performance and dry skin.

What are the best drinks for staying hydrated?

Water is a really good choice for children to keep well hydrated, and it’s good to introduce water as a drink early on so that children get used to the plain taste. Other drinks such as milk and fruit juice can also provide fluid and other nutrients. Pure unsweetened fruit juice and smoothies can count towards one of your 5-a-day, contributing useful amounts of vitamin C. However, they are quite acidic, and also contain natural free sugars, so they should be limited to no more than 150ml per day, ideally at mealtimes. Other acidic drinks, such as fizzy drinks and squashes, should also be limited or avoided altogether, even if they're sugar free – the acid can damage tooth enamel, and sugary drinks can lead to dental decay, as well as an excess of calories. It’s recommended that children should not consume caffeine-containing energy drinks.

How can I encourage my child to drink more water?

It’s a good idea for parents to act as role models, drinking water throughout the day, starting at breakfast time. As with fussy eating, if your child doesn’t seem to like drinking, it’s a good idea to stay calm. A few tips that you can try to encourage them to drink more, and to get used to drinking water include:

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  • Ensure children have a drink before school, i.e. with breakfast, and before and during playtime.
  • Offer drinks regularly, especially when the weather is warm.
  • Remember that many foods (such as fruit, vegetables and yogurt, milk on cereal, soup) have a high water content and can also contribute to fluid intake.
  • When out and about, or at nursery or school, pack a drink bottle filled with water.
  • Try and try again: repeated tastings may help children to develop a taste for water.
  • Let your child choose their own cup or water bottle and let them fill it themselves.
  • Add ice or a slice of lemon or cucumber to jazz it up a bit.

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This article was updated on 4 August 2020 by Tracey Raye.


All health content on is provided for general information only, and should not be treated as a substitute for the medical advice of your own doctor or any other healthcare professional. If you have any concerns about your general health, you should contact your local healthcare provider. See our website terms and conditions for more information.

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