This mechanism is unique to British Berkefeld water filtration cartridges for unsurpassed sealing and maximum biological protection. The design of the water filtration cartridges is 100% natural (submicro ceramic clay, and coconut shell charcoal), filtration threshold of 0.2 micron. The filtration of British Berkefeld cartridges helps to conserve minerals and trace elements. The passage of water is always from the outside to the inside of the water filter cartridge. With a nomadic British Berkefeld filter, filtration is instantaneous, without water discharge, without energy consumption, maintenance is simplified with an annual replacement (at most) of the water filtration cartridges.