This switch I am going to use for the emergency pump switch. I cleaned the existing standard type switch but it still is sticking on. So normally this switch will be above any standing water.
I looked at how the wire end seals into the plastic body, They used a white hard plastic like epoxy seal.
A failure could happen if that seal fails although it looks good. This switch is not flimsy or weak feeling.
I will add a little soft sealer to end where wire enters the switch just in case. And also use a bit of heat shrink tubing on the wires.
Plastic nut has a rubber seal, so it was designed to seal into a container with wires on the dry side.
I can mount the switch, then run heat shrink up over the threads and down onto the wires. and have some silicon gasket maker in between.
I have had Rule mercury switches fail in the wire. Somehow water got under the outer rubber covering and disintegrated the copper.