A good friend of mine, who is both a dentist and personal trainer, has already written about the perils of BPA bottles of water.
BPA is short for Bisphenol A which has been proven to cause changes in hormone levels (particularly oestrogen) as well as having carcinogenic effects – particularly in women causing breast cancer.
I recently ordered some (personalised) bottles from http://www.onegreenbottle.com/ which look great and are a lot better than drinking from regular plastic bottles. This website has also been setup to donate some of the proceeds to Breast Cancer UK.
They are not only very easy to carry around but also encourage regular rehydration because you always have water with you!