I have observed a potentially serious problem, at least in the Sears water distiller which I have.
The problem: When the unit is plugged in the entire inner stainless steel container carries full line voltage. I measured the voltage from the water inside the shell to ground (stainless kitchen sink) and it was 123 volts ac. In normal use this may not be a problem, as the plastic outer case of the distiller insulates the inner container. However, if the unit is left plugged in while refilling it there could be serious risk. I don't know if this is a general problem, or just a problem with my unit. I intend to ask Sears that question. Meantime, be aware of a potential safety risk! All the best, Dean