i find the opposite. i find if i have a 1 litre bottle it vanishes!! any smaller than that and i can't be bothered to walk across the office to refill it all the time and any bigger than that you can't drink from, but a litre goes really fast. i have to limit myself to 4 litres when i'm at work, at home i have a 75cl sports bottle and find it harder...
abz xx