The media used in our post filter elements can contain a small amount of harmless process dust or fines, due primarily to assembly, handling and shipping of these elements. For aesthetic reasons, we recommend the Berkey® Post Filter elements be purged to remove the majority of this process dust, prior to installing these elements in your Berkey® system.
If the Berkey® Post Filter elements are not purged prior to use, the possibility of turbidity in the first few cycles of water may occur. For the sake of simplicity, turbidity appears as cloudiness in the water. In other words, the process dust/fines are what cause the cloudiness.
For example, NMCL had the post filter elements tested to determine at what level the turbidity falls off. The results were as expected.
The laboratory tested the turbidity remaining after purging the Berkey® Post Filter elements (as described in the assembly instructions). The results show that the levels of turbidity drop off dramatically if the purging process is followed. It is recommended that the post filter elements be purged for approximately 30 seconds in each direction, prior to installation. For those purists, this purging process can be repeated an additional one or two times before installation.
Our lab tests determined that the turbidity drops off as follows:
One Purging: Turbidity reduced by >94%
Two Purging’s: Turbidity reduced by >96%
Three Purging’s: Turbidity reduced by >98%
The turbidity will continue to decline with each refill cycle of your Berkey® system. While turbidity may be aesthetically unpleasing, according to current research, there are no negative health effects with which to be concerned.