Firefighters are sounding the alarm about a surprisingly hazardous risk: leaving water bottles in cars on hot summer days. Despite the seemingly innocuous nature of water, the danger it poses under certain conditions is significant.

Experts highlight that when a plastic water bottle is left in direct sunlight, it can ignite a fire in a matter of minutes. This might sound counterintuitive, given that water is traditionally used to extinguish fires, but the risk is real and has been confirmed by recent tests.

With temperatures inside parked cars soaring dramatically in summer, it’s not hard to see how this happens. A study from Stanford University revealed that car interiors can reach temperatures between 112°F and 136°F (44°C and 55°C) on sunny days with ambient temperatures of 72°F to 96°F (22°C to 35°C) within just one hour.

Firefighters from the Midwest City Fire Department in Oklahoma have conducted experiments demonstrating that sunlight can be concentrated through a water bottle to temperatures of 250°F (120°C). This effect is similar to using a magnifying glass, where the water bottle’s clear material and liquid combine to focus sunlight intensely enough to ignite a fire.

David Richardson, a firefighter who participated in the test, emphasizes the seriousness of the risk: “The sunlight passes through the water and the clear bottle, acting like a magnifying glass to create a concentrated beam that can cause combustion.”

Engineer Dioni Amuchastegui shared a personal encounter with this phenomenon. While on a lunch break in his truck, he noticed smoke and discovered that light refracted through a water bottle was starting a fire on his seat.

Fortunately, Amuchastegui managed to address the issue before it escalated. However, the incident highlights a danger that many might not be aware of.

Were you aware of this potential hazard with water bottles in hot cars? I certainly wasn’t!