Guess im gonna be looking at some epoxy then. The water shouldn't get close to boiling as that what it takes to get the hot glue back to a soluble state.
Internal it is. I asked a few others they say the same.
Not sure about the epoxy vs/ hot glue. Haven't worked with either of them. Just make sure it's a watertight seal! Especially with heat too, because those buggers get hot.