Water is a basic nutrient for the human body and is critical to human life. This page explains how much of the body is made up of water and what the recommended daily intake of water is.
Our bodies are 50 to 60% water - indeed our brains are 75%, muscles 77 per cent and even bones 22%. Yet we have no means of storing it and need to keep topping it up to maintain our health.
The best way to top it up is to drink tap water. Estimates vary on the amount of liquid needed to prevent dehydration but many sources recommend 6-8 glasses of fluid or 1-2 litres per day with more for physically active persons or those exposed to hot environments.
Besides tap water, fluid can include milk, fruit, juice, tea and coffee.
Keeping hydrated is a central part of nutritional care and tap water is the best and cheapest way to achieve it
A very useful guide to checking your hydration levels is to look at the colour of your urine!
A pale yellow is fine, the darker the colour the greater the degree of dehydration.
Alongside heat and exercise a common cause of dehydration is alcohol and many of the symptoms of a hangover are caused by dehydration.