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This What Happens When You Leave Bottled Water in the Sun

Have you been hoarding pallet upon pallet of bottled water in your hot garage in preparation for the end of the world? Don't let your Armageddon stockpile sit around too long.
Photo via Flickr user Lora Rajah

Take note, Armageddon preppers: Your hoard might be turning toxic right now.

As if you needed another reason to avoid bottled water except in cases of, say, a history-making drought or a poisonous algae bloom in your municipal water supply, you can start worrying about how long that bottle's been sitting around in the sun.

A recent University of Florida study has found that the plastic most commonly used in water and soda bottles can release antimony and bisphenol A (the dreaded BPA) if it's exposed to heat over a long period of time.


BPA became a popular bogeyman about five years back when scientists discovered that some plastic containers could leach the compound into their contents. Although the FDA claims that it is continuing to study BPA for potential health risks, it has currently concluded that "BPA is safe at the current levels occurring in foods."

There's no question that, on their own, these are particularly nasty substances. Research suggests that BPA could alter hormone levels, cause heart problems, and even increase the risk of cancer. Ingesting antimony can cause stomach pain, diarrhea, vomiting, and stomach ulcers, and some studies have linked it to spontaneous abortion and retinal bleeding.

The University of Florida's Lena Ma and her research team studied the effects of that a four-week stint in a hot box could have on water safety. The bottles were made of polyethylene terephthalate (PET), which is generally understood to be BPA-free. Ma's team, however, did detect trace levels of BPA in the samples they analyzed. "In theory, the plastic should not contain BPA," Ma tells MUNCHIES. "One explanation is that during the manufacturing process, especially when recycled plastics are used, trace amounts of BPA may be present. It's an impurity."

The bottles were kept in a warm environment that reached 158 degrees Fahrenheit at its peak. The higher the temperature, the more BPA and antimony were released. But the researchers also found that the release rate actually slowed over time, suggesting that the plastics eventually stabilize.

The good news is that only one of the 16 brands of bottled water sampled exceeded the Environmental Protection Agency's safety thresholds for antimony, and all the BPA levels were below safe limits. Still, Ma says there's cause for concern—especially when it comes to what's being stored in plastic containers, especially milk and acidic beverages, including juice.

"I suggest people to be careful about how long the bottled water has been sitting. The recommended shelf life is one year," says Ma. "It is not a good idea to store bottled water in your car during hot summer under the sun. Similarly, it is not a good idea to store bottled water for long time, say half a year in a warm setting such as garage."

Moral of the story: Stick to tap water served in a glass. Just make sure it's lead-free glass.