Why when electronic devices when make contact with water, they malfunction?

Answer 1

the distance between contacts is very small and even water with a small amount of dissolved salts in it can conduct enough electricity over that space to short circuit the device. Often when a device short circuits, too much current flows and damages the device.

A device that is left to dry after being submerged in tap water has salts that dry on it. These salt particles are also bigger than the spaces between contacts and can cause short circuiting.

However, rinsing a device in deionized water and allowing it to dry completely before adding electricity can often save a submerged device from the recycling bin -- semiconductor manufacturers use gallons of deionized water per device during manufacturing to clean off chemicals and particles that would do the same thing described above.

Answer 2

The water gets into the device and creates short circuits on the circuit boards, burning the device out.

Answer 3

If the power is off, and remains off until it is completely dry, the device will not malfunction.

Answer 4

impure water conducts electricity, so a little water on your circuit board will have electricity going everywhere. Boom, you circuit board is short-circuited. Usually you can just take it apart, dry it off, put it back together, and you're ready to go again.