For years I've carried water bottles virtually everywhere I go, snazzy ones in bright colors, from the company known as Nalgene, an old standby for hikers and campers.
No more. Various studies have shown that the transparent, colored bottles from Nalgene, made from Lexan® polycarbonate plastic, have potentially terrible health effects. Check out the article "On the Trail of Water Bottle Toxins" for the evidence. Then throw away your transparent Nalgene bottle (plastic type no. 7) and get yourself one of the old school ones, made of opaque white plastic (no. 2), which are much safer.