Watch What Happens When You Leave a Water Bottle Inside a Hot Car

We’ve all heard the advice not to drink from a water bottle that’s been left inside the car on a hot day. But, there’s also a good reason to not leave it there in the first place. A clear water-filled bottle can magnify the sun’s rays and start a fire in your vehicle. Yes, it is likely rare to occur, but it has happened. 

A recent video posted on Facebook by Idaho Power, an electric utility company in the U.S., shows how it can easily happen when the bottle catches the sunlight in the right spot. It happened to battery technician Dioni Amuchastegui who saw smoke inside his car. 

“Sitting in the truck, [I] happened to notice smoke out of the corner of my eye and looked over and noticed that light was being refracted through a water bottle. It was starting to catch the seat on fire,” said Dioni. He found two burn marks on the car seat. 

To see how hot light can get when passed through a water bottle, Dioni recreated the scenario but using a non-contact thermometer this time. The light registered at 213°F (100 °C). “It’s not something you really expect, to have a water bottle catch your chair on fire,” he said. 

Fire officials in the U.S. are warning the public of the same thing. The U.S. Midwest City Fire Department (MCFD) conducted a test of their own and their temperatures reached 250 °F (121 °C), local news channel KFOR reported.

“The sunlight will come through when it’s filled with liquid and act as a magnifying glass as you would with regular optics,” said MCFD's David Richardson. “It uses the liquid and the clear material to develop a focused beam and sure enough, it can actually cause a fire, a combustion.” 

The risk for such an incident is low, but officials still recommend taking precautions. Take the water bottle with you when you leave your car. With the Philippines’ hot tropical climate, it’s not far-fetched to imagine it happening here as well. 

Other things you shouldn’t leave inside a car include: 

1. A handbag, electronics, and other valuables
Valuables inside a car in plain sight can make you a target for thieves. “It doesn’t matter if the alarm goes off,” Eva Velasquez, CEO and president of Identity Theft Resource Center, told Reader's Digest. “It’s attractive, and they’re going to grab it.” If you must leave things in your car, consider stowing them in the trunk where they’re out of sight. 

2. Sunglasses and other eyewear
Just like a water bottle, glasses can start a fire when left inside a hot car. “Especially avoid the top of the dashboard,” said American Optometric Association spokeswoman Susan Thomas. “The windshield will act like a magnifying lens.” Heat can cause plastic frames to morph as well. 

3. Sunscreen
When exposed to direct heat, a bottle of sunblock not only loses its protective properties but can also cause it to explode. There may not be an immediate danger to this, but you will have a mess to deal with. 

4. Passport and other personal documents
When we think of personal things of value, jewelry and even cash come to mind. Have the same mindset for important documents and your passport as well. “We have to think of data and pieces of our identity as valuables,” said Velasquez. Don’t be a victim of identity theft. 

[h/t: Country Living]