The Black Berkey Primer is a hand-powered priming pump that makes it possible to prime Black Berkey Elements easily offline, without the need for faucets or hose connexions.Priming the Black Berkey Elements saturates the filters with water prior to their use, allowing for clean water production anywhere.The Black Berkey Primer also purges (or back-flushes) the Black Berkey Elements using air instead of water to clean the proprietary pores of the compressed carbon filter wall.Purging the Black Berkey Elements accomplishes twoe tasks: (1) It clears the pores of debris that has accumulated with use, (2) reduces the amount of time & effort needed to dry the filter s prior to storing them.In addition, those who may be having difficulty priming their elements in a small sink, can use the Black Berkey Primer instead.With a Black Berkey Element properly immersed in water & attached to it, the Black Berkey Primer creates a simple pressure gradient which draws water into the centre of each Black Berkey Element.Once the Black Berkey Element is completely saturated with water, it passes through the Black Berkey Primer and squirts out of the opposite end.