Warning: Placing Water Bottles Wrong in Your Car Could Cause a Fire

  The Hidden Dangers of Misplacing Water Bottles in Your Car, Especially During Hot Summer Days

A Risky Habit: Leaving Water Bottles in the Wrong Spot

Summer is here, and once again we’re faced with the scorching sun that feels like it’s burning right through to the soul. Naturally, hot weather leads to dehydration, which means we get thirsty faster and need to drink more water. That’s why most people carry a water bottle with them wherever they go — to avoid the hassle of walking through the heat just to buy a drink.

If you own a car, there’s a high chance you’ve developed the habit of keeping a water bottle inside, often placing it on the dashboard or beside the driver’s seat for easy access. While this might seem harmless, it’s time to think twice — especially if your car is parked outdoors in the blazing midday sun. The consequences could be just as serious as what’s shown in the image below.

Why Water Bottles Can Cause Fires in Your Car

The reason is actually very simple: Most water bottles are made of clear plastic and have a curved, rounded surface. When filled with water, the bottle can act like a magnifying glass. Under direct sunlight, especially during midday, the temperature inside a parked car can reach up to 60°C (140°F). Sunlight passing through the window and then through the water bottle can focus into a single point, significantly increasing the temperature at that spot.

This concentrated heat can become intense enough to scorch surfaces or even ignite flammable materials inside the car.

In an experiment conducted by Dioni Amuchastegui, an electrical engineer in Idaho (USA), a water bottle was shown to concentrate sunlight and generate heat exceeding 100°C (212°F). If the bottle is placed on a dark surface — such as a car seat — the focused heat can become intense enough to ignite the material, potentially starting a fire and leading to a disaster.

In reality, for a water bottle to actually start a fire inside a car, several factors need to align — but that doesn’t mean it can’t happen. In fact, Amuchastegui himself nearly experienced such an incident, which is what led him to conduct the experiment and raise public awareness.

That’s why it’s important to break this habit before it’s too late. If you really need to keep a water bottle in your car, at the very least, make sure it’s properly covered and not left in direct sunlight or in a spot where sunlight can easily reach it.

Final Advice: Be mindful of where you place water bottles inside your vehicle, especially during hot summer days. A small act of caution can prevent a potentially serious accident.

Advice from Experienced Drivers

Seasoned drivers recommend that when parking under direct sunlight, car owners should make sure to place water bottles and other flammable or heat-sensitive items in shaded areas where sunlight can’t reach them, or cover them properly. While this may seem inconvenient, it’s a small effort that greatly enhances safety.

Additionally, if you often have to park your car under the hot sun, investing in a sunshade or protective car cover is highly advisable. It’s a simple yet effective way to care for and maintain your vehicle — something every car owner should keep in mind.