This video is a load of crap. The quality of your skin is the only thing measured in deciding if it's good for you or not and they make a wide ranging conclusion like they did? Common sense says that if you do a lot of excercise or if the climate is hot you need to drink more water. Like most of recent BBC1 though this program is aimed at the middle class 40+ age group who sit on their arse watching tv every evening and never do anything else, so it might apply to them.