The main goal of particle filtration is to remove suspended material such as: sand, rock fragments, and other debris from the water. In addition, the process can be used to improve the appearance of the water and protect equipment and plumbing from physical erosion or damage. If a UV system is used, the system typically requires pre-filtration to remove particles that may block the UV light. Most household filters are in the range of 1 to 100 microns, but for UV pretreatment a 5 to 20 micron filter is used. In some cases, well owners and city water users may install a point-oft filtration system that uses 0.25 to 1 micron (sub-micron) filters. Typically, these are sink or faucet-mounted systems or systems built into appliances to provide additional barriers because of Bacteria, sediment, Giardia, and other protozoans. In many cases these filters include activated carbon to help reduce levels of Chlorine and chlorine by-products.

Filtration can be divided into a number of categories:

Conventional particle filtration includes removal of particles that range in size from 1 micron and larger. This would include particles like gravel, coarse sand, sand, silt-size particles, larger protozoans like Giardia cysts ( 8 to 12 microns), Giardia trophozoites (10 to 18 microns), Cryptosporidium oocysts (4 to 5 microns), and larger clay minerals, but it would not include bacteria, clay particles, asbestos, or viruses.

Microfiltration would include  the removal of particles that range from 0.1 to 1 microns.  At 0.1 micron the filtration system should remove the smaller protozoans and bacteria, but  are not fine enough to remove all viruses, asbestos fibers, colloidal silicates, or fine clay particles.

Ultrafiltration would include the removal of particles that range from 0.01 to 0.5 microns by means of a membrane-based filtration process where a combination of pressure and concentration gradients causes contaminants to separate by passing through a semipermeable membrane.  At this size range filtration, the water would be free of most fine clay and virus particles, and free of protozoans and bacteria.

Nanofiltration would include the removal of particles that range from about 0.001 to 0.01 microns. This is also a pressure-membrane-driven process that should remove some dissolved solids, viruses, aqueous salts, pyrogens, and endotoxins.

Reverse Osmosis would include the removal of particles and ions that range in size from about 0.0001 microns to over 0.001 microns. Reverse osmosis has the ability to remove dissolved metal ions and dissolved salts. The removal rates for each ion vary as a function of the type of membrane, pH, temperature, and the presence of chlorine. Some membranes are very vulnerable to the presence of chlorine and, because the membranes can accumulate larger molecules and trap bacteria, they are vulnerable to biofouling.

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Follow the Path to Clean Water

We recommend that, prior to installing a CounterTop POU (Point-of-Use) Unit, you Get Informed by gathering as much information as possible and Get Tested by conducting multiple levels of testing depending on your needs: Level 1 Observational Testing using our Self Test Web App, Level 2 Do-It-Yourself Testing, Level 3 Informational Lab Testing and, if needed, Level 4 Certified Testing conducted by a water professional.

If you have any questions please Contact the KnowYourH2O team.