Hiking Filter. Part - 2
Viruses are extremely rare in natural water sources, but they are smaller than unicellular organisms and most bacteria, which allows them to slip through even microfilters. However, it is still possible to purify water from them.
Filters with pore diameters of no more than 0.02 microns can capture the most common viruses found in water environments — norovirus, rotavirus, and hepatitis A virus. These types of filters are called ultrafilters or purifiers. They are recommended for use during travels in third-world countries, tropical regions, and in emergency situations. They are also necessary when filtering water from a body of water located in close proximity to pastures and livestock watering points. However, even such filters cannot completely eliminate all viral infections from water, as some viruses can be smaller than 0.01 microns! Therefore, if the water source raises significant doubts, the filtered water should be additionally disinfected.
Sizes of household items and microorganisms, micrometers
700 Needle tip
200 Thickness of a razor blade
100 Flower pollen
80 Average diameter of a human hair
21x5 Giardia trophozoite, the active form of the unicellular parasite
0.8 Clostridium botulinum, bacterium. The causative agent of botulism
0.7 Salmonella enterica, bacterium. The causative agent of salmonellosis
0.4 Shigella dysenteriae, bacterium. The causative agent of bacterial dysentery
0.027-0.038 Norovirus
0.032-0.027 Hepatitis A virus
0.07 Rotavirus
Important
No modern hiking filter can make seawater or water with chemical contaminants from bodies of water in close proximity to agricultural land and mines safe for drinking. The filter cannot remove all viruses, chemical compounds, and radioactive materials, as well as particles smaller than the diameter of the filtering pores.
Hiking Filter. Part - 1