Flow Rate: Each filter will have an approximate flow rate of 1 gallon per hour under optimal conditions. Filtration rates may be faster depending on the size of unit used (i.e. larger units will have more water pressure available to force the water through the filters due to the added weight from more water). The rates listed on the website are faster because they were calculated when water is continuously and simultaneously removed from the lower chamber and added to the upper chamber.
Size: The Black Berkey Filters measure approximately a diameter of 2.25" and an approximate height of 8.5" excluding the stem. The total approximate length of the filter is 9.75"
Composition: Carbon composite containing high-grade coconut shell carbon combined with a proprietary blend of 5 other types of media.
Certifications: The Black Berkey purification element formulation has been tested by State and EPA accredited laboratories to exceed NSF/ANSI Standard 53 but has not yet been certified.