A coffee percolator is a type of pot used to brew coffee. The name stems from the word “percolate” which means to cause (a solvent) to pass through a permeable substance especially for extracting a soluble constituent. In the case of coffee-brewing the solvent is water, the permeable substance is the coffee grounds, and the soluble constituents are the chemical compounds that give coffee its color, taste, aroma, and stimulating properties.
A percolator is a pot consisting of two chambers. The bottom chamber holds the water for brewing. The top chamber is perforated and contains a filter, upon which the ground coffee is placed. A tube leads from the bottom chamber to the top of the percolator. The percolator is placed over a heat source such as a stove and the water is heated. As the water is heated and it starts to boil, it travels up the tube. The water then falls out of the tube and onto the ground coffee bed.
Percolator brewing was popular in the western world until the 1970s. It fell out of fashion due to the imperfect brewing process which leads to over extraction. This is due to the coffee being recycled and rebrewed multiple times throughout the brewing process.
An advantage of percolator brewing is that it requires no electricity, just a heat source, to function.