Here is a new hot-weather hazard that you’ve probably never considered: An Idaho Power Company worker was on lunch break when he noticed smoke coming from the center console of his truck. The culprit, he was surprised to learn, was a bottle of water. In a video Diono Amuchastegui shared to the company’s Facebook page, he says that when he got closer, he “noticed light was being refracted through a water bottle and starting to catch the seat on fire.” The video shows two burn marks left on the seat of his vehicle. Rare? Yes. But not so rare that it’s unheard of. In a test conducted by Oklahoma’s Midwest City Fire Department, sunlight magnified by a water bottle reached 250 degrees. When the sunlight comes through a plastic bottle filled with liquid, the bottle acts as a magnifying glass, and the result is a focused beam, which can cause combustion. Some fire departments are now warning people about this potential fire hazard.