The plastic used for bottled water is polyethylene terephthalate (PET), which the FDA has deemed safe for food packaging under normal use. In their statement, the FDA stated that the levels of chemicals that might leach into foods from plastic containers were well within the margin of safety. The evidence is ongoing regarding the safety of leaving plastic water bottles in extremely hot temperatures (>40C or 104F) for long periods of time. It’s also important to note that plastics not deemed safe for the microwave (i.e. margarine or yogurt tubs) should not be used to warm food.