Hepatitis A, Norwalk Virus
0.02 to 0.2 Microns Viruses can multiply only in living cells since they do not have their own metabolism. Their minimal size makes it difficult to mechanically filter them out of the water. For this purpose, filters with a pore size of <0.02 micro are required. Viruses sensitively react to heat and chemical disinfectants. The biologically grown diaphragms and bio film substrates present a good protection against virus since these viruses attach themselves to a host institution and can be extensively removed with up to 0.2 micron sized filter pores.