We frequently carry water bottles to quench our thirst, but there’s a crucial safety detail many overlook. Firefighters are raising awareness about a surprising risk posed by water bottles left inside cars. This everyday item could ignite fires.

Several years back, an Oklahoma firefighter illustrated how a water bottle, when exposed to direct sunlight in a vehicle, could ignite a fire. When placed under direct sunlight, the water bottle functions like a magnifying glass, concentrating the light into an intense beam capable of sparking a fire within minutes.

This occurs when a partially filled water bottle magnifies and focuses sunlight onto a specific spot, just as a magnifying glass would. Though it may seem like an unlikely scenario, the Oklahoma firefighter who showcased this danger revealed that he has personally seen it happen firsthand.

In one instance, he recounted a car seat that had been scorched by a beam of sunlight magnified through a water bottle. The firefighter noted that while this isn’t something most people would ever consider, it’s a legitimate concern, particularly during the sweltering summer season. He emphasized that the only surefire way to prevent this hazard is to ensure you never leave water bottles inside your vehicle.