Drinking Enough Water: How Much Is Enough
The figure of two litres a day is only a rough average. Your body has a far more accurate way of telling you — you just have to pay attention.
But · 4 min read · Sep 5, 2026
Water makes up most of your body weight and takes part in almost every process of life: regulating temperature, transporting nutrients, and carrying waste out through the kidneys. Even mild dehydration is enough to leave you tired, headachy and unable to concentrate, without your knowing why.
How much you need
Adults usually need about two litres of water a day, counting the water in soups, broths, milk, fruit and vegetables. That means the amount you actually need to pour into a glass is often less than that figure.
Your needs rise in hot weather, when you work outdoors, exercise, have a fever, diarrhoea or are vomiting a lot.
Signs your body is short of water
- Thirst, dry mouth, cracked lips
- Dark urine, urinating less often
- Tiredness, headache, difficulty concentrating
- Dry skin with less elasticity
- Dizziness when you stand up quickly
Older adults are the most prone to dehydration, because the sense of thirst fades with age. With the grandparents in your household, do not wait until they say they are thirsty before offering a drink — keep a glass of water within reach and remind them to sip a little throughout the day.
A few common misunderstandings
Drinking a great deal does not mean being healthier. Drinking too much water in a short time can dilute the sodium in your blood, causing nausea, confusion, and in severe cases seizures. This is rare but real, and is seen most often in people training at high intensity who replace their losses with plain water alone.
Coffee and tea still count towards your fluid intake, even though they have a mild diuretic effect. Soft drinks and sugary juices, on the other hand, are not a good choice for daily hydration.
With diarrhoea or a high fever, you lose mineral salts along with the water. In that case an oral rehydration solution mixed exactly as directed makes more sense than plain water alone.
A note for people with kidney or heart disease
If you have heart failure, kidney failure, severe liver disease or are on dialysis, your daily fluid amount must follow your doctor's individual instructions, and may be far lower than the usual figure. Following general advice can cause swelling and shortness of breath.
When to seek care immediately
Go to a medical facility if you or a family member is drowsy or confused, has not urinated for many hours, has a fast heartbeat or low blood pressure, or is vomiting and having diarrhoea continuously and cannot keep fluids down. Young children and older people dehydrate very quickly — do not wait it out at home.
This information is for general reference only and does not replace advice from your doctor.
