Dominic Lawson has a good rant about water in The Independent today.
He’s questioning why so many people are drinking so much water:
This organised panic about dehydration seems to stem from a misreading – quite possibly deliberate – of guidelines from the US Food and Nutrition Board in 1945. These stated that “a suitable allowance of water for adults is 2.5 litres daily in most instances. An ordinary standard for diverse persons is one millilitre for each calorie of food. Most of this quantity is contained in prepared foods.” As Shapiro notes, the last sentence of that advice is always left out, leading to the idea that we need an extra eight glasses of water over and above our actual requirements.
Apart from that, I’ve never understood why the same amount of water is recommended everywhere. If I’m in a really hot place, such as walking around in the midday sun in July in Spain or Georgia, I naturally drink lots of fluid. However, during winter in Scotland, I simply don’t feel the need to drink as much (which is natural given I sweat much less), but the water fanatics still claim I should drink the same eight glasses as in the Mediterranean summer sun.