For years, women have been glugging down eight glasses of water a day in pursuit of a glowing complexion (or feeling guilty if they didn't).
Now experts say that a balanced diet and lots of sunscreen are far more important in keeping wrinkles at bay.
The finding will come as a relief to those who have found the drinking regime something of an ordeal.
The widely-held belief that we need eight cups of water a day to keep the skin and body healthy was investigated by the British Nutrition Foundation.
Its 'Food for the Skin' review concluded there is no firm evidence to back up the theory.
Or, as the BNF put it: 'There currently appears to be very little scientific evidence relating to the effects of water consumption on skin hydration, and whether drinking more or less water actually has any impact on skin appearance.'
Researcher Heather Yuregir said: 'Drinking water for the sake of drinking water really has no effect on improving the appearance of skin.'
But diet and sun exposure really do affect complexion, she said.
Vitamins A, B, C and E, contained in a range of fruit and vegetables, help keep the skin elastic, protect it from age-related damage and help with the growth of new skin.
Not eating enough of them can cause problems such as scurvy and dry, scaly skin.
It is also clear that sun-worshipping ages the skin, causing mottling, a leathery texture and deep wrinkles.
Mrs Yuregir, a nutrition scientist, said: 'The common belief that drinking plenty of water is required for healthy skin appearance is actually not backed up by scientific evidence.
'Fruit and veg can keep your skin functioning as it should and keep it looking healthy.
'And sun cream is recommended to prevent the signs of ageing because the majority of signs of ageing that appear on the skin are caused by sun damage.'
The BNF review follows research published last year which concluded that drinking water does not help slimmers lose weight.
The weight and waist size of more than 1,000 young women was compared with the amount of water they consumed each day - both from drinks and food.
The Japanese study found no link between water in drinks, including water itself, tea, coffee, soft drinks and fruit juices, and body shape.
But foods rich in water, such as fruit, vegetables, soups and casseroles, appeared to help in the battle of the bulge.
This may be because water-rich foods are also high in fibre, making people feel full faster and stopping them from over-eating.