A medical practitioner has argued that the recommendation to drink six to eight glasses of water a day to prevent dehydration is not only nonsense, but is thoroughly debunk nonsense.
There is currently no clear evidence of the benefit from drinking increased amounts of water, yet the we-don't-drink-enough-water myth has endless advocates including the NHS, claimed GP Margaret McCartney.
The NHS Choices website states: Try to drink about six to eight glasses of water (or other fluids) a day to prevent dehydration.
While many schools also feel it appropriate to insist that pupils are accompanied to school by a water bottle, other organisations, often with vested interests, reinforce this message, she said.
For example, Hydration for Health (created by French food giant Danone - makers of bottled waters including Volvic and Evian) recommends 1.5 to 2 litres of water daily as the simplest and healthiest hydration advice you can give.
It also claims that, even mild dehydration plays a role in the development of various diseases.
But McCartney disagreed that that there is no high quality published evidence to support these claims.
While there are some conditions that do benefit from drinking increased water, such as in people with recurrent kidney stones, other evidence for preventing disease is conflicting, added McCartney.
There are many organisations with vested interests who would like to tell doctors and patients what to do. We should just say no, she concluded.