By Lindsey BeverThe Washington PostIs it true that you should not drink from plastic water bottles left in a hot car? And plastic water bottles. Single-use plastic bottles are made of a thin plastic known as polyethylene terephthalate, or PET. • Regularly swap out single-use plastic water bottles that are kept in the car to reduce potential exposures. The bottom line: It is best to avoid drinking water from single-use plastic bottles that have been in a hot car.