How much water should I actually drink?

The eight-glasses-of-water rule is repeated everywhere and has never been the official advice. What replaces it is both more relaxed and more useful.

Safety

Step by step

1. Start with the actual guidance.The NHS suggests six to eight drinks a day for most adults. That is a rough guide rather than a target, and it deliberately says drinks rather than water.
2. Count everything you drink.Tea, coffee, milk, squash, juice and soft drinks all hydrate. The idea that tea and coffee dehydrate you is not supported at normal intakes — the water in them more than offsets the mild diuretic effect.
3. Remember food contributes too.Roughly a fifth of most people's fluid comes from food. Fruit, vegetables, soup, yoghurt and cereal with milk all count, which is part of why rigid counting misleads.
4. Use urine colour as the practical check.Pale straw is where you want to be. Dark yellow suggests drinking more; completely colourless all day may mean you are drinking more than you need. It is free and it is immediate.
5. Allow for the obvious variables.Hot weather, exercise, illness with fever or diarrhoea, and physical work all raise the requirement, sometimes considerably. Body size matters too.
6. Know that thirst works.For most healthy adults it is a reliable signal. The main exceptions are older people, whose thirst response weakens with age, and during hard exercise where it can lag behind.
7. Recognise the signs of drinking too little.Dark urine, headache, tiredness, poor concentration, dry mouth, dizziness on standing. Mild dehydration is common and easily missed because it does not feel like thirst.
8. Know that too much is also possible.Drinking very large volumes in a short time can dilute blood sodium dangerously. It is rare, but it is a real risk in endurance sport and in deliberate over-drinking, so more is not automatically better.
9. Be careful with sugar rather than with water.Juice and soft drinks hydrate but bring sugar. Water, milk, tea and coffee without sugar are the sensible everyday defaults.
10. Take extra care in hot weather.Thirst lags behind loss when you are sweating. Drinking a little regularly is more effective than a large amount once you notice.
11. Pay attention with older relatives.Reduced thirst sensation combined with deliberately drinking less to avoid trips to the toilet is a common and genuinely risky combination. Offered drinks work better than reminders.
12. Stop counting if it is a chore.Attaching drinks to things you already do — kettle on, meals, arriving at a desk — works far better than tracking millilitres, and it lasts.

Tips

• Tea and coffee count. The dehydration claim does not hold at normal amounts.
• Pale straw urine is the one check worth knowing. It replaces all the arithmetic.
• Six to eight drinks, not eight glasses of water. The official figure was never water alone.

Common mistakes

• Treating eight glasses of water as a rule — It has no basis in UK guidance, ignores the fluid in food and other drinks, and makes a simple thing feel like a daily failure.
• Assuming more is always better — Very large volumes drunk quickly can dilute blood sodium, which is dangerous. Aiming for pale rather than colourless is the sensible target.

If it doesn't work

Questions people ask