~60%
Of your body is water
Water makes up around 60% of adult body weight and is needed for every cell.
Source: USGS / physiology texts
How much water should I drink a day?
UK advice on how much water to drink — 6 to 8 glasses a day — what counts, signs of dehydration and when you need more.
Last reviewed: October 2026 · How we check our content
Water in numbers
6–8
glasses (about 1.5–2 litres) of fluid a day — NHS advice
2.0 L / 2.5 L
total water a day for women / men from food and drink (EFSA)
~20%
of our water comes from food
Pale straw
coloured urine is a good sign you're drinking enough
What counts
Water
Tap water is the best choice — healthy and free.
Lower-fat milk
Also adds protein and calcium.
Tea and coffee
Count towards your fluid, though caffeine can affect sleep.
Sugar-free drinks
Better than sugary drinks, but water is best.
Fruit juice
Counts but limit to 150 ml a day because of sugar.
When you need more
- Hot weather
- Exercise and sport
- Illness with fever, vomiting or diarrhoea
- Pregnancy and breastfeeding
Signs of dehydration
- Feeling thirsty
- Dark yellow, strong-smelling urine
- Dizziness or light-headedness
- Tiredness
- Dry mouth, lips and eyes
- Peeing fewer than 4 times a day
Tip
Keep a refillable bottle with you and drink a glass with every meal — that alone gets most people to 6 glasses.
World health facts
All facts2–2.5 L
Daily water needs
Women need about 2 L and men about 2.5 L of total water daily from drinks and food — more in hot weather.
Source: EFSA 2010
2%
Dehydration that hurts focus
Losing just 1–2% of body water can reduce concentration, mood and exercise performance.
Source: Nutrition Reviews 2010
2.2B
People without safe drinking water
About 2.2 billion people still lack safely managed drinking water.
Source: WHO/UNICEF 2023
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Questions people ask
How much water should I drink a day UK?
The NHS recommends 6 to 8 glasses of fluid a day, about 1.5 to 2 litres, and more in hot weather or when exercising.
Does tea and coffee count as water?
Yes, tea and coffee count towards your daily fluid intake.
Can you drink too much water?
It is rare, but drinking very large amounts quickly can dilute sodium in the blood. Drinking to thirst is safe for most people.
Sources
- • NHS: Water, drinks and your health
- • NHS Eatwell Guide (6–8 glasses)
- • EFSA Dietary Reference Values for water (2010)
- • BDA Fluid fact sheet
General information based on UK public health sources, not medical advice. Speak to your GP, pharmacist or a registered dietitian before major diet changes or starting supplements, especially if you are pregnant, have a health condition or take medication.