Never Drink from Water Bottle Left in Car
- Mark Dworkin
- Sep 6
- 2 min read
Updated: Sep 8
St. Croix Times Staff
USVI - Researchers have revealed some alarming truths about plastic water bottles exposed to high temperatures. A recent study found that keeping polyethylene terephthalate (PET) plastic bottles at hot temperatures can cause dangerous chemicals like antimony and bisphenol to seep into the water.
Antimony is a heavy metal linked with symptoms like headaches, dizziness, nausea, vomiting, and sleep disturbances. Over time, it can even cause lung inflammation and stomach ulcers. Bisphenol has been associated with increased risks of cancer, fertility issues, autism, heart disorders, and premature death.
As temperatures rise inside a parked car, especially on a warm day, these chemicals become more likely to contaminate your water bottle. The Centers for Disease Control and Prevention (CDC) have shown that car interiors can hit 109 degrees within just 20 minutes on an 80 degree day, and even soar to 123 degrees in an hour. With those temps, your water isn’t as safe as you would think.
Generally heat and plastics don’t mix well. A 2025 study examined the various levels of microplastics found in 31 popular drinks. It found that hot beverages are the primary source of microplastic exposure, whereas cold drinks had significantly fewer microplastics. In previous studies, researchers examined how different temperatures and UV exposure affected plastic water bottles left in hot cars. They discovered that the plastic water bottles released tiny microplastic fragments, and not just a few. During testing, the plastics released billions of microplastic particles into the water. This has also been found to be true of cases of water stored in a hot garage for long periods of time. In contrast, the bottles kept in a refrigerated environment released almost none.
To reduce exposure, experts recommend avoiding long term storage of bottled water in hot conditions and opting for reusable glass or metal bottles instead.
It’s probably best to skip that sip of bottled water that has been sitting in your cup holder all day.
