It is always best to pre flush your new water filter before connecting to your machine to eliminate any air pockets or carbon resin from getting into the machines internal parts

Just push the switch and flush the filter into a container and remove any carbon & air pockets, when the water is clear open it up and let the clear water flow.

The BWT flush valve saves you time & money, no disconnecting the coffee machine water connection every new filter change or having possible damage to your machine from filter carbon build up .