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If you're confused about how much water you really need, I'm not surprised. Conflicting advice in recent headlines appears to contradict the old '8-glasses-a-day' advice we all grew up with. Is it necessary to chug down eight glasses of water daily, or is this recommendation exaggerated and out of date?

We've heard for years that eight glasses of water daily is the minimum necessary to keep healthy. Your weight loss and health depend on it. Drink the minimum and see clearer skin, better sleep, better sex (we hope), improved vision (now I'm pushing it).

We're warned of impending dehydration without at least eight glasses. But, the tide has turned, away from liquid nutrition toward examining your daily diet, including what you eat, as well as what you drink.

The answer is: you need what you need. If it's summer, you need more. If you're exercising, you need more. If you're a normal sedentary person, who's not perspiring, and not exercising more than 15-20 minutes daily, Dr. Heinz Valtin of Dartmouth Medical School says you need no more than four glasses of water daily.

Although the World Health Organization recommends that everyone drink a minimum of two litres of water daily, or about eight glasses (200 ml each), the old '8x8' rule is based on studies performed on people under extraordinary circumstances including soldiers at high altitude and hospitalised patients. What you and I need is different.

How important is water?

There is no debate that water is important. Nevertheless, it has not been scientifically determined that the amount recommended for all these years is right for all people. Kidney experts state that the average-sized person living in a temperate climate needs about one litre, or approximately four eight-ounce glasses of fluid daily; some of this fluid may be obtained from food. Fruits and vegetables are mostly fluid, and contribute to the minimum fluid requirement, plus they add fibre to your diet.

People take water for granted. Do you know that your entire body chemistry and metabolic functions depend on getting adequate hydration? More than half the weight of the human body is water, which forms the basis of all body fluids, including digestive juices, blood, urine, lymph and perspiration.

All cell processes and all organ functions depend upon water. Water is necessary for digestion, for elimination (and to prevent constipation) and for regulating your body temperature by distributing heat and cooling the body via perspiration.

Can you drink too much water?

It's very difficult to drink too much water, but it's possible. Excessive water consumption can result in hyponatraemia, a medical term for low sodium (salt) in the blood. Hyponatraemia's symptoms include extreme diarrhoea, headaches, confusion, weakness and sometimes personality changes. The most severe cases will result in seizures, respiratory arrest, coma and death.

However, drinking too much water, or water intoxication, is not common. Most people can handle at least eight glasses a day. Dr. David Katz, Associate Clinical Professor of Public Health and Medicine at the Yale School of Medicine, says, "In general, healthy people cannot drink too much water. Normal kidneys can handle up to 12 litres per day".

Dr. Katz said certain medical conditions preclude drinking too much water, including kidney failure and heart failure; people under a doctor's care will follow their physician's medical advice. But, for the rest of us, drinking eight 200 ml glasses per day is not an unreasonable goal, although far less important for sedentary people in cool environments than for those active in the heat. "For most healthy people, thirst is a good guide."

How much do we really need? And where should I get it?

Here are my best tips for staying hydrated:

1. How much water you need depends upon your weight, your activity and your climate. If it's hot, and you're exercising, you’ll surely need more water than when you're sitting at a computer all day.

2. Fresh fruits and vegetables add fluid to your diet. You're going to benefit from the water in these foods. Lettuce is 97 to 98 percent water; and so is watermelon. Other good fluid sources include carrots, (88 percent water), fresh tomatoes (93 percent water), and fresh celery (94 percent water).

3. Since cooking vegetables decreases the fluid content, eat a big, fresh salad every day, and at least four servings each of fruit and other vegetables.

4. With age, we need more water, because we become less sensitive to body losses and our sense of thirst diminishes.

5. Clinical evidence shows that people with a history of kidney stones can lower their risk for reoccurrence by increasing their fluid intake.

6. Drink more water if you're exercising and perspiring a good amount, especially in a dry climate.

7. Water is the best fluid you can drink. It has no calories, additives or preservatives. I drink tap water because my county council produces a high quality product at an inexpensive price. In fact, regulations on tap water are more stringent than those on bottled water, and the average bottle of water usually costs more than a litre of petrol or milk.

8. In terms of weight loss, drinking water will not cause you to lose weight, but use water as a strategy or tool to help when you’re on a programme to lose weight. Drinking water between meals can help curb your appetite, and so will snacking on water-filled fresh vegetables and fruit.

9. To prevent dehydration, remember these simple guidleines:

• Drink water before, during and after exercise
• Drink water every 20 minutes or so when engaged in strenuous physical activity
• Do not take salt tablets
• Stop working out at the first sign of dizziness, lightheadedness, or fatigue

So keep a bottle of water with you at all times.

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