Firefighters are cautioning the public about the dangers of leaving plastic water bottles in cars, which can start fires under certain conditions. The risk comes from sunlight passing through the water, acting like a magnifying glass.

When sunlight shines through a water-filled plastic bottle, it can focus light onto a flammable surface, potentially igniting a fire. Firefighters have demonstrated how quickly this can happen, even within minutes. In one incident, a firefighter from Idaho found his car seat smoldering after sunlight, refracted by a water bottle, focused onto the upholstery.

To prevent such fires, firefighters recommend not leaving water bottles in cars, especially in direct sunlight. If necessary, store them in shaded areas or use opaque bottles. Public awareness campaigns aim to spread this message and reduce the risk of vehicle fires.