The human body is two-thirds water. Water is essential nutrient that is involved in every function of the body. It helps transport nutrients and waste products in and out of cells. It is necessary for all digestive, absorption, circulatory, and excretory functions, as well as for the utilization of the water-soluble vitamins. It is also needed for the maintenance of proper body temperature.

Water must be continuously replaced since on average 250ml is lost on a daily basis through breathing. Nutritionists have difficulty in suggesting an exact daily requirement because the amount of water required will vary depending on the on the climate and whether any type of activity is undertaken. By drinking an adequate amount of water each day-at least eight glasses (2 litres) -you can ensure that your body has all it needs to maintain good health. 

Your fluid needs might be double or even triple that amount when you work out for more than an hour in the heat. Even on cool days and shorter workouts, you still need to drink more than nonathletes.

You can live without food for several weeks, but you can go less than a week without water. The best way to get this water is by drinking plain water. But other beverages, such as fruit juices, milk, and noncaffeinated drinks are also good sources of water. Fruits and vegetables can also be good sources of water.

Caffeinated and alcoholic beverages, while they do supply water to the body initially, contain diuretics that cause the body to lose water.

It would appear that most people do not drink enough water. The classic signs and symptoms include:

• Headaches
• Poor concentration
• Tiredness
• Increased risk of developing kidney infections, and
• Constipation.

It is almost impossible to drink to much water, although if large volumes of water are taken in a short space of time it can provide short lived symptoms similar to being drunk.