The most important thing between waterproof and non-waterproof micro switch is IP Rating. Generally, the IP Rating could from IP00 to IP69K, which means the dustproof and waterproof level. Detailed explanation clicks to see. For example, a IP67 Rating micro switch, the “6” mean dustproof level and the “7” means waterproof level. An ip67 approved micro switch is better than an ip65 one, ip65 is better than ip64.
When we meet a micro switch but we don’t know it’s IP rating, we can distinguish from its appearance. If a switch with a rubber band as this picture show, yes, it should be the waterproof type, like Zing Ear G3, G5W11, G9, G10B serious.
On the other hand, we can recognize from the Terminal Type of a micro switch. We can see they are Wire or PCB or Solder terminals. Usually, the wire type is better than the PCB and Solder terminal.
However, the waterproof type micro switch is sealed in construction so the operating temperature is lower than the non-waterproof type. For example, the G5W11 is 40t85 but the G5H serious max temperature is t150.
All in all, why we need a waterproof or non-waterproof micro switch is dependent on the application.