Why does a plastic water bottle sweat?

Ditto to what's already been said. Just to add - if you look up “dew point” you'll find all you need about the phenomenon. read more

The inner temperature of plastic water bottle is different from outer temperature. Inner temperature of water bottle is more than outer. So, a natural mineral water bottle shows sweat in its inner layer. read more

The air above the surface of the water bottle becomes colder as heat is exchanged between the air and water bottle. When that air drops in temperature, it means it can hold less moisture in it. The moisture that can no longer be held in the air forms water droplets on the water bottle. read more

this is due to condensation. when the water vapour in the atmosphere(moisture), comes in contact with the surface of the cold water bottle the water in the atmosphere having higher temp. condenses on the surface of the cold water bottle. read more