What Makes Water Bottles Sweat?

Ever wonder why water bottles sweat? That is, why do they get wet on the outside the container for no apparent reason?

The answer is simple and it’s called “condensation“. When air is cooled quickly the evaporated water that it holds begin to condense, meaning that it gets squeezed out of the air and forms water droplets on the surface of surrounding objects.

Condensation is also what causes dew to accumulate on the grass on cold mornings. When the temperature drops the air can hold less water than it could when the air was warmer. Warm, humid air therefore is very conducive to condensation. The amount of the evaporated water that air can hold is directly correlated to the ambient temperature, in fact.

You may have noticed that your water bottle only starts to sweat when you have cold liquids stored inside of it. You will probably only get water droplets on the surface of the bottle after it is removed from the refrigerator or if you have put ice cubes inside the bottle to cool down your beverage.

What happens is the cold water bottle cools the air that is surrounding the surface of the bottle. As the air cools, it can hold less water and the excess water is squeezed out in the same way one might squeeze water out of a sponge.

The water condenses right out of the air itself and deposits itself on the surface of the water bottle, making it seem like the bottle is sweating. It appears that the water bottle may actually be leaking or spilling liquid, but it is actually just the wonderful process of condensation that is causing this phenomenon.

So don’t sweat it when your water bottle sweats. It is a very natural and interesting environmental process that is causing it and nothing to be alarmed about.

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