There are three key methods for removing caffeine from regular coffee beans: The most common use a solvent and the last simply use water.

They take green coffee beans, soak or steam them until the caffeine is dissolved or their pores are opened, and then extract the caffeine from the green coffee beans.

Water methods are considered chemical-free, the solvent method relies on ethyl acetate (naturally found in some fruits) and methylene chloride (commonly used in industrial applications).

The Swiss Water Process and Mountain Water Process are used to make the best decaf coffee, which is what we use. This tends to produce the most flavorful coffee, Ristenpart says, because it’s good at removing caffeine and without stripping other flavors from the green coffee beans. However, it’s also more expensive to use the Swiss Water Process and Mountain Water process to remove caffeine from coffee beans, and the process is difficult to produce at scale. 

How much caffeine in decaf coffee is a question we are asked, and none of these methods scrubs the bean of caffeine completely? Usually, 97 percent of caffeine is removed from the coffee beans, some decaffeinated coffees can still contain between 3 and 12 mg of caffeine per cup of coffee.