The importance of hydration - why we need plenty of water to stay healthy

08 February 2023

We need lots of water to allow our bodies to function properly. Even mild dehydration can have lots of adverse effects on our health, ranging from kidney stones and joint pain to a general lack of get up and go!

Here, we explain how much water we need to stay hydrated, examine the benefits of increased hydration, and offer some tips on how to boost your fluid intake.

Fact or fiction? We are 80% water

Fiction: there is a lot of water in our bodies, but while water makes up around 75% of an infant's body weight, it only accounts for around 55% of the weight of an elderly person.1

Why is it so important to stay hydrated?

Drinking enough water every day can help to improve your mood, your concentration levels, and the quality of your sleep.

In fact, figures suggest that being even slightly dehydrated can make it harder to remember things, as well as potentially making you more emotional and anxious.

Being well hydrated also keeps your joints lubricated and your organs and cells functioning properly, helping to prevent a range of health conditions, such as:

  • Urinary tract infections (UTIs)
  • Headaches and migraines
  • Kidney stones
  • Skin conditions
  • Constipation

Other reasons to drink the recommended daily amount of water include:

  • It helps you digest your food properly - being properly hydrated can stop unpleasant symptoms such as bloating, heartburn, and gas
  • A lack of fluids slows down your circulation and forces your heart to work harder pumping oxygen around your body - this can leave you feeling tired and sluggish
  • Staying well hydrated can boost your metabolism and help you avoid seeking out sugary snacks - so drinking more water can help you to lose weight
  • Taking on more water aids your body's detoxification systems - this allows your body to dispose of waste and harmful substances more effectively

Know your numbers

A typical adult should drink between 1.5 and 2 litres of fluid each day.2

How much should I drink to stay hydrated?

The NHS recommends drinking six to eight glasses, which equates to 1.5 litres to 2 litres of water per day. However, some American medical associations advocate drinking more than 10 glasses per day if you can.

Whatever water intake goal you set yourself, the easiest way to achieve it is to start drinking in the morning and continue to do so regularly throughout the day.

Not all the liquid you take in has to be water, of course. Other healthy sources of hydration include low fat milk and low sugar or sugar-free drinks such as cordials, tea, and coffee.

Some foods also have a high-water content, meaning incorporating more of them into your diet can help you to stay better hydrated.

Cucumbers, tomatoes, and melons, for example, are all more than 90% water.

Did you know

Around 20% to 30% of the fluid our bodies take in comes from foods.3

What liquids can I drink to stay hydrated?

Drinking any liquid will help to hydrate your body. Water is the number one choice because it is free (from the tap) and contains no calories or sugars that can damage your teeth and overall health.

Other drinks the NHS recommends drinking to stay hydrated include:

  • Sparkling water
  • Tea, coffee, and herbal tea (with no added sugar)
  • Semi-skimmed, 1% fat or skimmed milk
  • No-added-sugar squash or cordial
  • Unsweetened fruit juice (1 small glass a day)

Drinks that should only be enjoyed in moderation include:

  • Milkshakes and flavoured milk
  • Flavoured water (try plain water with a slice of fruit instead)
  • Fizzy sodas
  • Alcohol
  • Sweetened fruit juice
  • Energy drinks

Know your numbers

A 240ml glass of shop-bought orange juice contains around 110 calories and 21g of sugar.4

How can I tell if I'm dehydrated?

Your body will become dehydrated more quickly if you have an illness that makes you vomit or have diarrhoea or if you sweat a lot due to fever, hot weather, or exercise.

Drinking alcohol also increases dehydration levels as it causes our bodies to pass more urine than usual.

But other than feeling thirsty, what are the main signs that you are dehydrated?

Symptoms to look out for include:

  • Dark yellow urine - generally speaking, the lighter your urine the better
  • A dry mouth - or dry lips or eyes
  • Dizzy spells - or light-headedness
  • Headaches - dehydration can cause your brain to shrink temporarily
  • Pain when urinating - often a sign of a UTI
  • Low blood pressure - staying hydrated increases blood flow

Fact or fiction? Drinking coffee dehydrates you

Fiction: caffeine is a diuretic that can cause us to urinate more frequently. But the fluid taken in when drinking a cup of coffee or tea easily outweighs this, boosting overall hydration.5

Stay hydrated with these five top tips!

1. Always carry a water bottle

This allows you to keep an eye on how much you're drinking and means you can hydrate at any time.

2. Have a cup of tea (or lots of them)

Black tea, green tea, fruit tea; they're all good for hydrating your body. Just avoid the caffeinated versions in the evening.

3. Drink water before and after meals

Getting into the habit of drinking a glass of water before and after every meal will increase hydration and help to prevent you overeating.

4. Eat water-rich foods

Fruits and vegetables such as celery and melon have a high-water content, as do fresh soups and broths.

5. Download a water reminder app

If you find it hard to remember to drink water throughout the day, an app that reminds you when to have a drink could be handy.