The short answer to this question is yes. It is completely normal, in fact, your Berkey® system is not designed to fully drain from the top chamber once it reaches the bottom plastic base of the Black Berkey® Elements. It really is all about “head pressure.”
Think of it this way: When the top chamber of your Berkey system is full of water waiting to pass through the Black Berkey Elements, the weight of the water exerts pressure against the proprietary carbon body of the filters. As the water makes its way through the filters and into the lower chamber, the water level in the top chamber drops, also exerting less pressure against the filters.
As long as the Black Berkey Elements were fully primed when they were set-up and installed (the carbon was completely saturated with water molecules) or if there are no or low amounts of contaminants that are trapped in their carbon-block bodies (for filters already in use), then the water level in the top chamber should drop down to the plastic base portion of the filters.
If the water level remains an inch or two (or higher) above the plastic base, then it is likely that the filters are
- not fully saturated at that level and have air molecules trapped (common with brand new filters), or
- the filters have contaminants that are reducing/preventing water flow (commonly occurs with filters already in use).
In both cases, the Black Berkey Elements should be scrubbed with a slightly abrasive scrub pad or brush and then re-primed/purged. Re-priming is always the last step to perform after scrubbing them. This ensures that the carbon fines (the fine black particles of loosened carbon) have been cleared from the pores of their carbon bodies, restoring optimal flow of water through the filters.
Re-priming or purging the Black Berkey Elements can be best accomplished with either the Black Berkey Primer™ manual hand-pump, or with a kitchen faucet or water hose using the thick tan priming washer that comes with each new set of Black Berkey Elements.
The Black Berkey Primer was created as an option to easily prime your Black Berkey Elements for use in off-grid and emergency conditions where in-line plumbing is not available. By switching the positions of the black end parts of the primer, you can push air into the filters, accelerating their drying. The manufacturer recommends the Black Berkey Elements to be bone-dry to the touch in order to prepare them for storage.