Widespread NHS advice to drink six to eight glasses of water a day to prevent dehydration is ‘thoroughly debunked nonsense’, argues a GP in the BMJ.

Writing in the medical journal yesterday, Dr Margaret McCartney, a GP in Glasgow, argues water consumption at this level is not supported by evidence, but is often repeated by NHS and industry-funded advice bodies.

Dr McCartney questions advice on the NHS Choices website that encourages patients to ‘try to drink about six to eight glasses of water (or other fluids) a day to prevent dehydration’.

After looking at the evidence for this claim, she says: ‘Water is not a simple solution to multiple health problems.’

‘There are many organisations with vested interests who would like to tell doctors and patients what to do. We should just say no.’

Speaking to Pulse, Dr McCartney explained that she wanted to stop people from thinking about ‘waterlogging’ their body to keep healthy.

‘The general appetite for health tips and advice hasn’t dampened down, despite the fact that there’s nothing new in preventative medicine – don’t smoke, don’t eat too much, drink water and exercise regularly,’ she said.

The UK Government recommends six to eight glasses of water should be consumed everyday is to replace water losses, based on the average diet and metabolism of a 70kg man.

A Department of Health spokesperson said: ‘Our advice is based on the best available evidence. We will assess any new information as it becomes available.’

BMJ, published online 12 July 2011