The composition of the Black Berkey® elements used in Berkey® water purifiers is a unique formulation protected by a patent. It is based on the mix of six different and specific types of media, which includes high-quality activated carbon. Compiled in a very compact matrix containing millions of microscopic pores, they create a "tortuous path" through which water can pass, but contaminants cannot. These channels are so thin that all undesirable elements are inevitably trapped. With a process of absorption and adsorption, submicron viruses are also blocked, something other water filters cannot do without the use of chemicals.

The cylinder of activated carbon is impregnated with an ion-exchange resin. The activated carbon adsorbs or chemically binds to organic compounds, such as solvents and petroleum-based fuels, a large number of pesticides, and numerous pharmaceuticals. The ion-exchange resin eliminates many dissolved metals from the water by exchanging toxic heavy metals (like lead, mercury, and cadmium) for lighter and inoffensive metals (like sodium, the main component of table salt). All this enables a comprehensive and highly efficient filtration.

Additionally, the manufacturer Berkey® New Millennium Concept Ltd. confirms that graphene oxide is not used in the composition of Black Berkey® filters.

More details can be found on the page explaining the functioning of Berkey® water filters.