Why on earth do all these people pay through the nose for something that you can get free from the tap?
Panorama did a programme about it back in February of this year, showing the damage that bottles of water have on the environment, testing to see if you could really tell the difference, showing how water is taken from one area for sale in the UK while the natives are dying from not having access to decent water.
Panorama Bottled Water
To be honest, I think it is just a fashion statement really... completely unnecessary, and pointless. I personally keep two 3l bottles in the fridge which I fill up from the tap whenever I empty them, so I always have cold water in the fridge whenever I want it for free.