Decaf Coffee and You
When you drink Decaffeinated coffee you’re not quite getting caffeine-free coffee; all coffee has some caffeine in it. United States federal regulations require that coffee labeled as "decaffeinated" must reduce its caffeine level by 97 .5%.
This isn’t as radical as it sounds. Arabica coffees are already about 98.64% caffeine-free. Robusta beans are a bit more, but the process is the same. Carbon Dioxide, water, Ethyl Acetate and other solvents are used to decaffeinate coffee to reduce it to between 2 to 4 milligrams of caffeine per cup. When the required amount of caffeine has been removed only .0408 % of the remaining coffee weight is caffeine. At this level it may be labeled "decaffeinated.”
Various brands of coffee may advertise different levels of caffeine, but they’re splitting hairs. Most decaf coffee contains the same amount of caffeine: some, but very little. So if you’re avoiding caffeine for your health, you can worry about taste or price instead, but if your avoiding it for other reasons, like religion, then it’s best to avoid coffee altogether.