Water is conductive – it is a pathway for electricity to travel through. When you get water on an electronic device that is powered on / charged, you’re introducing pathways for the electricity to go to places where it’s not supposed to go, and that can damage those parts of the computer so that even after the water dries up, the electricity isn’t going where it was supposed to go originally according to the original design of the part.
Waterproofing just helps keep water out of parts where electricity/electrons are flowing. If the water can’t get there, it can’t open up those other pathways to fudge up the part.
Latest Answers