'World Cup water bottles' in Russia warned to be unsafe

Ball-shaped water bottles are on display in a supermarket in Russia.

Before the World Cup, mineral water manufacturer Svyatoi Istochnik launched this bottle model and immediately, the ball-shaped product "sold out" in supermarkets and convenience stores. The neck of the bottle also has a handle for easy carrying.

But scientists soon pointed out a safety flaw in the design: if the ball-shaped bottle was left in the sun for about a minute, the object behind it would catch fire.

Why does this happen? In terms of optical principles, a spherical water bottle is a converging lens. Sunlight, when passing through a spherical object containing liquid, will converge into a beam, directed at a point. This principle is similar to the way people often use a magnifying glass to burn leaves or paper.

When enough heat is applied, especially in strong sunlight, the light passing through the spherical water bottle is strong enough to burn many things.

In fact, fire departments in the US often advise drivers not to leave water bottles (which are always partially spherical) in areas where the sun shines. With a completely spherical bottle, the risk of fire is obviously even higher.

Previously, few people talked about this problem with water bottles because spherical water bottles were very rare.

Despite criticism from scientists, the manufacturer, Svyatoi Istochnik, has refused to accept responsibility and advised people to keep the bottles away from sunlight. In shops in Moscow and Petersburg, the product is still widely available.

However, with Russia's sunny summer, World Cup visitors should be careful with this round soccer ball-shaped water bottle.

Huy Dang