Activated carbon is widely used in filtration systems, from air filters to blood filters. It’s essentially a form of charcoal with a very high surface area. This adsorbs a wide range of molecules that it comes into contact with. Activated carbon filtration systems for water can trap and remove a large percentage of impurities in water. Activated carbon filtration is common in bottleless water systems; however an even higher percentage or impurities can be removed using reverse osmosis.