Apparantly the 'science' behind the 8 glasses a day, isn't. It's promoted and supported and advertised by the bottled water industry, and humans, who evolved in dry grasslands, are actually very, very good at managing water balances even when water is scarce. Too much water is actually bad for us.
http://www.bbc.co.uk/news/magazine-24464774
cheers,
Toddy
http://www.bbc.co.uk/news/magazine-24464774
cheers,
Toddy