We may not need to drink eight glasses of water a day after all, Canadian and American experts say.

Since the end of the Second World War, many people assumed they should drink at least eight glasses or two litres of water per day to maintain a healthy lifestyle. Countless weight loss and fitness magazines have reinforced the idea.

University of British Columbia nutrition Prof. Susan Barr is part of a joint Canadian and American team of doctors and nutritionists who are looking at how much water people actually need.

Scientists are rethinking whether we need eight glasses of water a day

Barr said they couldn't find any scientific evidence to support the eight to 10 glass recommendation.

The confusion may have arisen because a typical adult's energy requirements call for two to three litres of fluid – but it doesn't all have to be in the form of glasses of water. All foods and non-alcoholic drinks count toward the goal.

For example, Barr said:

• broccoli is about 90 per cent water
• bread is about 35 per cent water
• meat, fish and poultry contain 50 to 60 per cent water

As for drinking water to lose weight, Barr said, "If you drink a lot of water, right at the moment you will feel full. But half an hour later, your stomach will be empty and you'll be hungry."

So far, the researchers say it seems most North Americans are getting the necessary amount of water from their diet.

There have been cases of people drinking too much water. Confusion, headache and cramps are symptoms of drinking too much water. A few deaths have been linked to excessive water intake while taking the party drug, ecstasy.

On the other hand, people who are exercising and sweating more than normal need to replenish the vital liquid to avoid dehydration.

Recommendations on exactly how many glasses people should try to drink are expected in the fall.