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Water and Hydration
Water is essential for life — aim for 6 to 8 glasses of fluid a day, more in hot weather or when active. Dark urine is a sign to drink more.
What it is
Water makes up much of the body and is essential for nearly every function. Hydration comes from drinks and from the water in food.
What it does
It helps regulate body temperature, transports nutrients, removes waste, keeps joints lubricated and helps the brain and body work properly.
Good sources
Water, lower-fat milk, sugar-free drinks, tea and coffee all count towards fluid intake; many foods, especially fruit and vegetables, also contain water.
Deficiency and who is at risk
Not drinking enough causes dehydration, with signs including thirst, dark yellow urine, headache, tiredness and dizziness. Older people, young children and those who are unwell are more at risk.
Balance
Can you have too much?
Drinking extreme amounts of water in a short time can rarely dilute the blood’s salts dangerously (hyponatraemia), but this is uncommon. For most people, drinking to thirst and keeping urine pale is a good guide.
Education and reference only. This is general nutrition information, not personal advice, and does not give doses. Ask a pharmacist, GP or registered dietitian before starting supplements, especially with a health condition or in pregnancy.
Answers
Water and Hydration: frequently asked questions
How much water should I drink a day?
UK advice is around 6 to 8 glasses (about 1.5–2 litres) of fluid a day, including water, lower-fat milk and sugar-free drinks. You need more in hot weather, when exercising, or if unwell.
How can I tell if I am well hydrated?
Pale, straw-coloured urine usually means you are well hydrated, while dark yellow urine is a sign to drink more. Thirst, headache and tiredness can also indicate you need fluids.
Related
More on others and nutrition
Sources
Where this is drawn from
- NHS — Eat well
- British Dietetic Association (BDA)
- UK Scientific Advisory Committee on Nutrition (SACN)
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