Water makes up a large part of your body and plays a part in nearly everything it does. You lose some every day, so you need to replace it. The good news is that you do not need to be precise.
The official numbers
- NHS (UK): Citing the Eatwell Guide, the NHS suggests 6 to 8 cups or glasses of fluid a day. It calls this a guide only.
- EFSA (EU): In 2010 the European Food Safety Authority said a daily water intake of 2.0 litres is adequate for women and 2.5 litres for men. That page is now more than ten years old, so treat the figures as a reference point rather than a personal target.
Your own needs depend on your size, the weather, your diet and your activity.
What counts
The NHS says that water, lower-fat milk and lower-sugar drinks, including tea and coffee, all count. Food also provides some fluid.
Are you drinking enough?
The NHS offers an easy check: your pee should be a clear, pale yellow colour. If it is dark, drink more. You do not have to count glasses all day.
When you need more
The NHS says you may need more fluid if you are:
- pregnant or breastfeeding;
- in a hot environment;
- physically active for long periods;
- ill.
It also advises drinking extra if you have been sweating from physical activity. For a normal gym session, sip water before, during and after, and drink to thirst.
Water and workouts
For a normal gym session, drink a glass of water in the hours before, sip during, and drink again afterwards. The NHS advises drinking extra if you have been sweating from physical activity. Most people do not need special sports drinks for an ordinary gym session, and many of them contain sugar. Read the label if you do use one.
Tea, coffee, milk and juice
- Tea and coffee: count toward your fluid, according to the NHS. Watch the sugar and syrups.
- Lower-fat milk: also counts.
- Fruit juice and smoothies: the NHS suggests no more than 150 ml a day with a meal, because of the sugar.
- Fizzy and energy drinks: the NHS suggests choosing sugar-free options where you can.
Sugary drinks
Drinks with sugar add calories and can damage teeth. The NHS suggests that adults:
- swap sugary drinks for diet, sugar-free or no-added-sugar versions;
- limit fruit juice and smoothies to a single small 150 ml glass a day, taken with a meal;
- avoid high-sugar drinks too often.
For children, the NHS suggests avoiding sugary fizzy drinks, squash and juice drinks entirely. For the sugar limits behind this advice, see how much sugar per day, and read about hidden sugar.
Simple habits
- Keep a bottle with you. If it is in front of you, you will sip.
- Drink a glass with each meal.
- Have water before, during and after training.
- Add flavour without sugar, such as a slice of lemon or cucumber, or a sugar-free squash.
- Check your pee colour once or twice a day.
What about “eight glasses”?
You may have heard “drink eight glasses a day”. The NHS’s “6 to 8 cups or glasses of fluid” is a similar idea but includes drinks other than plain water. It is a guide, not a rule.
Frequently asked questions
Does food count toward my water intake?
The NHS notes that foods also provide some fluid.
Do I need to drink more in hot weather?
Yes, the NHS says you may need more in a hot environment.
Is clear pee a good sign?
The NHS check is a clear, pale yellow colour. If yours is darker, drink more.
Can I drink too much?
It is unusual, but forcing very large amounts is not helpful. Drink regularly and listen to your thirst.
If you are always very thirsty, pass much more urine than usual, or have medical conditions that affect fluid, speak to a doctor. Do not force huge amounts of water.