ATER IS A KEY NUTRIENT that is absolutely essential for good health. Every physiological process depends upon water for it to take place. It is necessary for digestion, absorption, production of energy, and maintenance of body temperature. It is also
needed for circulation, and for transportation of nutrients to cells and waste products out of your body. Water is the principle component of your body, making up about 60 percent of your body weight.
Water is essential to good health, but how much water should you drink each day? The answer to this question is important because, on the one hand, you should not want to be even mildly dehydrated, but on the other
hand, you do not want to consume excessive water simply out of worry that your water intake might be inadequate.
The “8 x 8 Rule”
Health experts generally recommend that a healthy adult needs about 8 cups of water per day. This is generally referred to as the “8 x 8 rule”: drink eight 8-ounce glasses (or cups) of water a day. That is a total of about 2 litres of water per day.
When you try to apply this rule in practice some questions immediately come to mind: Does an athletically active adult need the same amount of water as an adult who is essentially sedentary? Are your needs the same in winter and summer? Should you include juice, milk, coffee, and beer in your water intake or is it 8 glasses of plain water that you need?
To understand the answers to these questions, it is instructive to understand how the “8 x 8” rule is derived. The Derivation of “8 x 8” Rule
It is first estimated that an average adult living in a temperate climate loses about 10 cups of water a day—6 cups in the form of urine and 4 cups through breathing, sweating and bowel movements. So, the average adult needs to balance these water losses by consuming 10 cups of water a day. 2 cups of water are estimated to be furnished by food; that leaves us with the 8 cups of the “8 x 8” rule to be supplied by fluids. Now that you understand how the rule is derived, you are better positioned to understand the answers to the

questions that were raised above. First, the 8 cups of water that you need can be supplied not just by plain water but also by beverages such as juice, milk, coffee, and tea. Alcoholic beverages should not be counted as contributors to your daily water needs since alcohol increases urination.
Second, the standard recommendation is based on an average adult living in a temperate climate going about his normal daily business. The actual individual needs vary depending upon a number of factors.
Factors that increase your water needs
The following factors increase your water needs beyond the standard recommendation:
Exercise: Exercise raises your metabolism and makes you sweat, so you need to drink extra water to compensate for the fluid loss. How much additional fluid you need depends upon the intensity and duration of exercise and upon how much you sweat during exercise. Experts recommend that you drink two glasses of water about two hours before exercise. During exercise, start drinking fluids early, and continue to drink at regular intervals during and after exercise to replace the fluids lost.
Weather: During hot or humid weather you need to increase your intake of water to replace the fluid losses that occur with extra sweating.
Illness: When you have fever, vomiting or diarrhea, your body loses additional fluids. In these cases, you should drink more water. Similarly, you may need to increase your fluid intake if you have a bladder infection or kidney stones.
Pregnancy and breast-feeding: Women who are expecting or breastfeeding need additional fluids to stay well hydrated. Pregnant women should drink about 10 cups of fluids daily and women who breast-feed should consume about 13 cups of fluids a day. When you’re getting enough water, your urine should flow freely, be light in colour and free of odour. Dark urine with strong odour is a tell-tale sign of inadequate water intake.