Is It Safe to Drink Water from a Plastic Bottle Left in a Hot Car?

Leaving a plastic water bottle in a hot car may seem harmless, but heat can change what’s inside. Learn what happens to the water, and why fresh, cool water is always the safest choice.

On a warm day, many of us leave water bottles in the car without thinking twice. But what actually happens to that water when the car gets hot? Is it safe to drink later? Let’s take a closer look.

When a plastic water bottle sits in a hot car, the heat can cause the plastic to break down. Some studies show that very small amounts of chemicals, like bisphenol A (BPA) or antimony, can move from the plastic into the water. These chemicals have been linked to health problems when people are exposed to them in high amounts over a long time. The good news is that the levels found in bottles left in the heat are usually very low and not considered dangerous for most people.

Still, there are other things to think about. Heat creates a perfect environment for germs to grow, especially if you’ve already taken a sip from that bottle. Bacteria from your mouth can get into the water, and when it sits warm for hours, it may multiply. Drinking that water later could upset your stomach or make you sick.

So, what’s the safest choice? Try not to leave plastic water bottles in your car, especially on hot days. If you need to keep water with you, a reusable stainless steel or glass bottle is a safer option. For peace of mind, you can also bring a fresh bottle each day instead of reusing one that’s been sitting in the heat.