Berkefeld filter
![Schematic diagram of a Berkefeld filter](/Images/godic/202412/24/Schematic_diagram_of_a_Bakerfeld_filter4644.JPG")
A Berkefeld filter is a water filter made of diatomaceous earth (Kieselguhr). It was invented in Germany in 1891, and by 1922 was being marketed in the United Kingdom by the Berkefeld Filter Co. Berkefeld was the name of owner of the mine in Hanover, Germany, where the ceramic material was obtained.