How much water should you drink every day?

How much water should you drink a day?

How much water you need is unique to you and will depend on your health, age, size and weight as well as your activity levels and the climate you live in. Drinking little and often is the best way to stay optimally hydrated.

In the UK, the Eatwell Guide suggests we consume 6-8 glasses of water or other liquids a day, with more fluids being required in hot weather and when exercising. This amount should replace your normal water loss, which is typically about 1.2 to 1.5 litres – this means each glass consumed should hold about 200ml of fluid.

Hydration levels are topped up by the moisture in the food you eat – with food thought to contribute as much as 20% of your fluid intake.

The amount a child needs also varies - as a general rule of thumb, children aged four to 13 should drink approximately six to eight glasses of fluid a day, with younger children needing smaller servings – about 150ml for a four-year-old and 250ml for an older child.

Learn more about your child’s hydration needs.

What are the benefits of drinking water?

Nearly two thirds of your body is water, so it's clear how important it is to stay well hydrated. Hydration is needed for digestion, for our heart and circulation, for temperature control and for our brain to work well. Water is, without doubt, the single most essential component of the human body.

1. Drinking water may boost mental performance

Research suggests that losing as little as 1% of your body weight in fluid may reduce mental performance, as well as potentially induce fatigue and headache. This mild level of dehydration can easily occur over the course of a normal day’s activities, which highlights how important drinking little and often is for your health.

2. Drinking water may boost mood

Being dehydrated can affect our mood and well-being, with studies suggesting that energy levels, cognition and emotions may all be affected.

3. Drinking water may boost physical performance

If you exercise, some studies suggest that as little as a 2% loss in your body’s water content may impact how well you perform. Dehydration may compromise your body’s ability to control its temperature, it may increase feelings of tiredness and, unsurprisingly, make exercise more difficult. However, research in this area is conflicting. One small study on dehydration in athletes suggests it made no difference to their performance. Clearly other factors besides temperature, climate and endurance also play an important role.

What are the symptoms of dehydration?

Typical symptoms include:

• thirst
• passing dark-coloured urine
• needing to visit the toilet less often
• feeling lethargic or dizzy
• being unable to concentrate
• headaches
• having a dry mouth and lips

Checking the colour of your urine is considered to be the easiest and most practical way to assess hydration needs. You should pass urine which is light yellow to clear in colour. If you’ve been ill with diarrhoea and vomiting or fever, you can become dehydrated quickly unless you replace the extra water lost from the body. In certain circumstances rehydration solutions may be useful because they help to replace the water, salts and minerals that your body has lost. If you are experiencing this, the NHS recommends that you consult a pharmacist who may recommend oral hydration sachets, and speak to your GP if your symptoms don't improve with treatment.

Babies, children and the elderly are the most at risk of dehydration. Visit the NHS website to find out the signs of serious dehydration in adults and children under five.

Do liquids other than water count?

Water, milk, sugar-free drinks and tea and coffee all count, but remember that caffeinated drinks like tea and coffee can make the body produce urine more quickly. Fruit juice and smoothies also count, but because they contain ‘free’ sugars (the type we are encouraged to cut back on), you should limit these to a combined total of 150ml per day.

Many of the foods we eat contribute to our fluid intake – for example, dishes like soup, ice cream and jelly, as well as fruit and veg with a high-water content, such as melon, courgette or cucumber.

Tips for staying hydrated

• Set yourself a daily goal, appropriate for your age, gender, size and activity levels. Remember you will need to drink more if you’ve been exercising, have been unwell or are in a hot climate.
• Fill a reusable water bottle or cup at the start of the day and drink regularly – check how well you are doing at key points through the day – set reminders if need be.
• If you find plain water unappealing, flavour water with fresh fruit or dilute cordial.
• Choose meals with a high water content, this may include soups and smoothies as well as salads – read more about hydrating foods.
• Take a full glass of water to bed with you and drink it before you rise in the morning.

Can you drink too much water?

It is possible to go the other way and drink too much, although for most people with healthy kidneys this will be managed by urinating more frequently. Hyponatraemia is a condition where the concentration of sodium in the blood is abnormally low, this may be caused by too much water combined with fluid retention. Athletes who participate in endurance events and take on too much fluid may be at risk of this condition as well as the elderly and those on certain prescription drugs.

Read more about how to stay hydrated while exercising.

When should I refer to my GP?

If you have not passed urine for more than eight hours, you feel light-headed or lethargic, are suffering confusion or have a rapid pulse rate, refer to your GP or healthcare practitioner. You may also wish to consult your GP if you have been experiencing consistent thirst, because this can be a symptom of a chronic health condition, such as diabetes.

Now read...

Is fruit juice good for you?
Top 5 health benefits of drinking water
The health benefits of coconut water
How to eat in a heatwave

This article was last reviewed on 15 April 2024 by Kerry Torrens.

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