Normally, approximately 2.5 litres of water is required daily for a fairly sedentary adult in a normal environment to replace the total loss of water that occurs though urine, faeces, skin and lungs.

To replace the water loss about 1 to 1.2 litres needs to be in drinks, (mainly water or cold herbal teas), 0.9 ml is taken though food and 0.3ml will be made by the body (oxidative metabolism).

What happens if you don’t drink enough water?

1. The pulse rate goes up and there is an increase in the rectal temperature

2. Respiration rate goes up

3. Numbness and tingling are experienced in the extremities

4. Increase in blood concentration

5. Diminution of blood volume and more difficult circulation

The difficulty and inadequacy of the circulation of blood under these conditions leads to:

1. breathing difficulties

2. gastrointestinal upsets

3. feelings of sickness and not wanting to eat

4. if it carries on for an extended period it will cause problems with muscle movement and unstable emotions

In a scientific study involving animals, the restriction of water gave rise to irritabliity and for some, bad temper.

Thirst

It has been demonstrated that under intense physical activity a male will only drink voluntarily around 50% as much water as what is required to replace losses from urine and sweat. Only after rest and food do the cravings for the required amount of water return to replace the fluid deficit.

Hot Drinks

After drinking hot liquids, the internal temperature of the body rises, resulting in sweating. This cools the body down. This is sometimes used in the practice of medicine when an increase in body temperature is required for a short time, or whether sweating is required. So it is preferable to choose cool or cold drinks rather than hot ones to replace fluid losses, particularly if hot drinks are the only types of drinks that are normally chosen.

Sugar drinks

During physical activities lasting less than 90 minutes, water is generally the beverage of choice, however, the inclusion of small concentrations of carbohydrate (6%-8% carbohydrate) have been shown to better sustain power output over water alone during physical activities that produce fatigue in 60 minutes or longer.