Black Berkey Primer The Black Berkey Primer is a hand-powered priming pump that makes it possible to prime Black Berkey Elements easily, without the need for faucets or hose connections. 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, for storage 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 center 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. The Black Berkey Primer is the easiest way to prime Black Berkey Elements. Please note this primer is only for Black Filters.