It’s pretty obvious that Americans are rather fond of bottled water. Consider that in 2017 alone, bottled water sales totaled $18.5 billion. But there might be one drawback to bottled water’s popularity – at least when it’s warm.

Heating Up

Such is the opinion of a team of researchers from University of Florida’s Institute of Food and Agricultural Sciences. Specifically, this group contends that consumers should be wary of drinking from water bottles left in warm places for long periods of time. The authors published their work in the September 2014 issue of the Journal Environmental Pollution.

The reason for this cautionary advice is that water bottles are made from plastic. When heated, plastic bottles can produce chemicals that are not safe for human consumption. For their study, the authors exposed bottles from 16 brands of bottled water to 158℉ temperatures. These bottles were forced to live with such conditions for four full weeks.

The good news is that, at the end of this time period, only one brand of water bottle had dangerously high levels of antimony and bisphenol A, the latter known as BPA for short. Despite this finding, senior study author Lena Ma stated that more research is needed to determine if such bottles remain safe to drink from following prolonged exposure to heat.

Different Drinks, Different Results?

The authors note that other beverages bottled in plastic containers might become contaminated in hot environments. “More attention should be given to other drinks packaged with polyethylene terephthalate plastic, such as milk, coffee and acidic juice,” noted Ma. “We only tested the pure water. If it is acidic juice, the story may be different.” In the meantime, the study authors did provide two recommendations regarding bottled water storage during summer months.

First, bottled water should not be left in garages for weeks on end. And second, consumers should avoid leaving plastic water bottles in their vehicles over the span of an entire day.