I know lots of sources say don't reuse/refill plastic water bottles because something in them leaches out into the water and is carcinogenic. My question is, if that's the case, why doesn't it leach out into the water that originally came in them in the first place? Is it because tap water has chemicals in it like chlorine and flouride that causes this to happen? And if it is, then why doesn't it happen to Dasani which says on the label that it's municipal water enhanced with minerals for taste. My water is from our private well, is untreated, and was just tested and passed with flying colors last October and tastes great. Can anybody enlighten me?