I agree 2 litres of water does little harm to the average paper pusher. The kidney does it's job just fine retaining salt and removing excess water in our body For high perspiring sportsmen such as badminton in tropical climates on a sunny afternoon I would have to differ water to favour a warm bowl of chicken soup, bone soup or something else granny can cook up. Here's a point to ponder. If we start out with 20litres (random figure) in our body and perspire and exhale out 1 litre in the next hour of badminton with no fluid intake does that leave us with 19litres of water in our body? No urination took place in that one hour.