Additional information to the first review
The white residue left behind inside the boiling chamber is not polishing compound, it is mineral scale. If you left it there, you would find that it builds up over time to a rather thick hard coating, which sometimes will chip off.<br /><br />You may remember Sears used to sell these units for $89-$99, until they went to a new design and then stopped carrying them altogether. Sears also sold a cleaner for these units, which they may still do (although the previous commenter's suggestion about using 9% vinegar plus some table salt sounds like a fine one).<br /><br />You do not actually have to clean these after every use. In fact, unless you get an unwieldy amount of scale build-up, you don't have to clean them at all; merely rinse the inside before adding more water to start another cycle. If you don't rinse, that can affect the taste of the finished product (we never bothered with the charcoal "after filter"; just threw it away and never replaced it). And if you don't clean, that supposedly will make it a little less efficient, although I've not really found that to be the case.<br /><br />If I remember correctly--and if this uses the same components--these units take 5-6 hours to distill a full gallon. What makes this design superior (there are several other brands with this same design) is its ease of cleaning. The kind of distiller which uses an internal float mechanism is a bear to clean and I don't recommend them for that reason.<br /><br />The weak point for this type of distiller, with the thermal cut-off, is the cut-off itself. That will die after a number of cycles and then you will end up throwing the whole unit out. I've been distilling water at home for 25 years and got so tired of this with the Sears units that I figured out where the cut-off was, and how to replace it, and never had to buy a new one after that. I'm not particularly mechanically adept, so that tells you how easy it was to do.
Rating: 5 stars