Others here have already covered bisphenol A, so I won't get into that. bpA doesn't even apply to PET plastics anyway.
I am going to rain on everyone's parade regarding contaminants in PET bottles though, and hopefully provide some perspective on the issue.
Every drop of water that occurs in nature has other molecules and "contaminants" in it, with contaminant being anything that isn't H2O. Water exists naturally as a solution, and our bodies evolved with the ability to process water as a solution.
Current FDA standards make our tap water pretty darn safe to drink. Bottled water is not as strictly regulated as tap water, so that is something to be cautious about- but since most bottled water is just tap water with possibly some extra filtering, it is a relatively safe option too.
PET bottles can
leech particles into the water, and they are more likely to when left in high heat... but that does not mean that those particles are necessarily toxic
or detrimental to your long-term health in low quantities. It is also a question of exposure- how often do you leave a PET water bottle in high heat for a season and then drink from it? Current research suggests that the occasional few hundred parts-per-billion of plastic molecules you would ingest are not going to hurt you, in the near-term or long-term. If you are still worried about it, you can limit your exposure by rotating any water stored in these containers.
PET plastics do allow odors to permeate through them over time (especially the super-thin eco models), so if you store a PET bottle of water in your trunk and let it sit for a year through the seasons, it will probably taste bad... but it shouldn't make you sick. I store some bottled water in my car, but I rotate it out seasonally.
"OK, just to be safe, I'll store the water in a steel container because that doesn't leech anything."
Wrong. Metal containers leech particles too.
But, whether it's PET or steel, the concentrations are infinitesimally small. So... don't worry, because you can't win
Also worth noting, I keep some of my emergency water stored in PET bottles specifically because they are very useful for emergency water purification. Say what? Look up the SODIS method
of water purification and be enlightened!
I guess what I'm trying to say is, in the grand scheme of things it is not something worth worrying about that much, especially if you limit your intake of water from PET bottles to begin with. Rotating the water you store in such bottles will reduce your health risk from "probably-nonexistent
" to "seriously, you're still worrying about this?