The common belief that people should drink eight glasses or two litres of water a day is a 'myth' that needs debunking, a Melbourne academic says.

The new Australian recommendations suggest an adequate daily fluid intake is about 2.8 litres for women and 3.4 litres for men. However, this includes fluid found in food and beverages. People could get their daily fluid intake from fruit, vegetables, juices and even tea and coffee.

"If you're feeling thirsty then drink by all means a beverage. It doesn't have to be water,' the Australian and New Zealand Journal of Public Health said.

"I'm not saying you shouldn't drink water. I'm saying the need to drink two litres of water on a regular basis is a complete myth. "We should be telling people that beverages like tea and coffee contribute to a person's fluid needs and despite their caffeine content, do not lead to dehydration,' Tsindos said.

He said that drinking a large quantity of water in one sitting to reach the daily intake level was pointless because it would not be distributed where it was needed. It would just dilute the urine. Drinking large amounts of water to lose weight would not work either without a low-calorie diet, he emphasised.