Coffee and Caffeine FAQ

Percolators violate most of the natural laws about brewing coffee.
o Don't over extract the oils and flavor. Percolators work by taking coffee and reheating it and throwing it over the grounds over and over and over again.

o Never reheat/boil coffee. This destroys the flavor. For best flavor, boil the water, pass it over the grounds and retain the heat. Don't reheat it.

Violating these rules may not sound like much, but these are about the only rules there are. The effect of a percolator is to keep passing boiling water/coffee over the grounds until there is no flavor left and the flavor in the coffee is so dead that it's a worthless waste.

There seems to be a great deal of misunderstanding about the re-boiling of already brewed coffee.

About half way through this video from "Coffee brewers institute" (1961) there is a good example of the boiling and re-brewing over and over again of coffee in a percolator. At approximately the 7 minute 40 second mark they show a glass percolator. If you look in the bottom half you will see already brewed coffee. The already brewed coffee is boiling and being pushed back over the grounds. That's a pretty good visual demonstration of what is happening.

Reading several comments some seem to be people who are not talking about a percolator but a vacuum pot or a moka pot.

If you have a brewer that pushes water up into a second (usually upper) chamber by steam and holds the water in the upper chamber during brewing then pulls it back via vacuum into the lower changer after brewing that's not a percolator. That is a vacuum pot which is described over here. Vacuum pot coffee also happens to be one of my favorite ways to have coffee.

A moka pot unlike a vacuum pot will push the water through the grounds and into an upper chamber that it is served from. I realize that in a few cases manufacturers have chosen to add the word percolator to the description of their moka pots. Strictly speaking this is not any more correct than calling a moka pot an espresso maker which is another common marketing gimmick for moka pots.

To further clarify (I hope) I am going to add a "typical" picture of each of the three confused types of coffee makers: