When people say "Don't drink the water", or if there is a boil alert, it usually means that there is some pathogen in the water. Giardia, Cryptosporidium, e.coli, salmonella are the most common pathogens that can make you sick, sometimes VERY sick immediately.
Cysts (giardia and cryptosporidium) 4-5 microns
Cysts are relatively easy to remove with a 0.5 micron or 1 micron carbon block filter. Because of their size, they won't be able to make it through the small openings of the carbon block filter. They can also be removed with ceramic filters, reverse osmosis, UV light or Purogene.
Bacteria (e.coli, salmonella, legionella) 500 nanometer to 1 micron
can be done in several ways
. Bacteria are smaller than cysts, so are harder to remove mechanically. Ceramic filters are 0.5 micron absolute, and 99.9999% rejection at .2 microns, which makes them very effective at removing bacteria. The problem with ceramic filters is that the flow at 60 PSI is only about 1 gallon per minute. Our South of the Border
system uses the Doulton RIO 2000 and is the only ceramic filter we have that can remove bacteria
at the high flow required for point of entry filtering. It does this by using six separate ceramic filters in a jumbo size to get to about 6 GPM.
Reverse Osmosis and UV are also effective in killing or sterilizing bacteria.
If you normally fill your tank and use the water using your pump, we have an additive called Purogene that can be used as an additive to kill any bacteria, algae, giardia and other organisms that might get into your tank. It is EPA approved at 5PPM for drinking water systems and is widely used in the airline industry for their water systems.
Viruses (<100 microns)
Free floating viruses are very small and cannot be mechanically removed reliably, even with Reverse Osmosis. Luckily, viruses usually attach to a larger host, like a bacterium or sediment. To effectively remove viruses, you need UV light or Purogene.