Why does minty gum make cold water colder?

Chewing minty gum does not actually change the temperature of water. The sensation that minty gum makes cold water colder is a perceived effect caused by the way the gum interacts with certain receptors in the mouth.

When you chew minty gum, the menthol present in the gum activates the TRPM8 receptors in your mouth, which are responsible for sensing cold. This creates a sensation of coolness in the mouth, which can trick the brain into feeling like the water is colder than it actually is.