The beverage called coffee is the result of mixing dry coffee with water. The combination can be done by one of many methods - ranging from the very simple, with the minimum of equipment - to the use of complex coffee machines which can cost thousands of dollars. Understanding a few facts about coffee brewing can help answer some of the questions which arise when wondering which brewing method to use.

A single coffee bean is an extremely complex entity, being composed of literally hundreds of substances, many of which are water-soluble. Nearly one-third of these water-soluble compounds can be removed in normal extraction processes. The goal of brewing coffee, however, is not to extract the greatest number of elements from ground coffee, because not all of them are desirable.

Expert tasters generally agree that the overall coffee flavor, which consists of color, aroma, taste and body, is best when about 18-22 percent of the flavor components have left the solid coffee and infused into the water. When more then 22 percent of the extractable materials permeated into the water, over-extraction occurs and harsh flavors are added to the brew, as the last substances to leave the grounds are unpleasant and bitter.

A second technical consideration is that, even if only the best flavored components have been extracted from the coffee, the cup flavor can be too concentrated or too diluted, depending on how much water is used. Again, most expert tasters generally agree that a cup of coffee tastes best when the liquid consists of between 98.4 - 98.7 percent water and 1.3 - 1.6 percent "soluble solids", the latter being what would be left if a cup of liquid coffee was reduced back to dry ingredients by an evaporation process. This ideal coffee strength is easily achieved by controlling the proportion of ground coffee to water, which for European tastes ranges between 50-75g per 1 liter of water. Many would consider normal strength coffee as one brewed at about 55g per liter of water. Much of North America drinks a weaker cup.

The most beautiful and expensive coffee machines do not always produce the most satisfying cup of coffee, and when choosing coffee-brewing equipment, consideration must be given to whether the design allows for a correct balance of brewing factors, as well as taking into account various safety aspects.