The filter consists of an unglazed porcelain tube that contains a ring of enameled porcelain through which the inflow pipe fits. The core of the porcelain is made up of a metal pipe with holes through which water flows out and is collected. Inflow is pressurized so filtration occurs under force.
There are 13 types in general: L1 to L13. L1 filters have the coarsest pore size while L13 have the finest.
It is as useful as other ceramic and porcelain filters. It is a good bacterial water filter used mainly as a high volume water filter. The filter works more quickly when the water supplied is under pressure. As other filters of its kind, it cannot filter very small particles like viruses or mycoplasma. It is used in removal of organisms from a fluid culture in order to obtain the bacterial toxins.