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Types of Water Filtration

In this blog, we will dive into different types of water filtration systems; where we aim to give an overview of the most common systems found in homes, along with insights into the functionality and advantages of each system.

Understanding Filtration Systems and Flow Rates

• Different systems have varying flow capabilities, typically measured in litres or gallons per minute. Point-of-use (POU) systems, designed for single-tap use, usually exhibit higher filtration capabilities but lower flow rates compared to point-of-entry (POE) or whole-house filters.

• Whole house systems are much larger units and have lower micron filtration capabilities (usually 1 – 5 microns).

• The higher the filtration, the slower the flow.

• Reverse osmosis and ultrafiltration always have slower flow rates due to the intense filtration process.

Exploring Reverse Osmosis Systems

• Reverse Osmosis (RO) Systems use a process that reverses water flow in a natural osmosis process so that water passes from a more concentrated solution to a more dilute solution through a semi-permeable membrane. Pre- and post-filters are often incorporated along with the reverse osmosis membrane itself.

• With pore sizes as small as 0.0001 microns, RO systems is very effective in removing protozoa, bacteria, viruses, and various chemical contaminants. 

• Reverse Osmosis Systems will remove common chemical contaminants (metal ions, aqueous salts), including sodium, chloride, copper, chromium, and lead; may reduce arsenic, fluoride, radium, sulfate, calcium, magnesium, potassium, nitrate, and phosphorous.

• The Reverse Osmosis system removes magnesium and calcium, which in turn lowers the PH of the water; this can cause an offensive taste. Some RO systems will address this by adding minerals (remineralize) after the RO process, raising the PH alkaline and improving taste.

Microfiltration (most whole house systems)

The most common whole-house systems are 5-10 microns.

• A microfiltration filter has a pore size of approximately 0.1 microns (pore size ranges vary by filter from 0.05 microns to 10 microns);

• Microfiltration lower than 1 micron has a high effectiveness in removing protozoa (for example, Cryptosporidium, Giardia);

• Microfiltration has moderate effectiveness in removing bacteria (for example, Campylobacter, Salmonella, Shigella, E. coli);

• Microfiltration is not effective in removing viruses (for example, Enteric, Hepatitis A, Norovirus, Rotavirus);

• Microfiltration is not effective in removing chemicals.

• Microfiltration is commonly used as a pre-filter for UF and RO and helps extend the life of these filters.

Ultrafiltration

• An ultrafiltration filter has a pore size of approximately 0.01 micron (pore size ranges vary by filter from 0.001 micron to 0.05 micron; Molecular Weight Cut Off (MWCO) of 13,000 to 200,000 Daltons). Ultrafiltration filters remove particles based on size, weight, and charge.

• Ultrafiltration is very effective in removing protozoa (for example, Cryptosporidium and Giardia).

• Ultrafiltration is very effective in removing bacteria (for example, Campylobacter, Salmonella, Shigella, E. coli).

• Ultrafiltration has moderate effectiveness in removing viruses (for example, Enteric, Hepatitis A, Norovirus, and Rotavirus).

• Ultrafiltration has a low effectiveness in removing chemicals.

Ultraviolet Treatment Systems (with pre-filtration)

• Ultraviolet Treatment with pre-filtration is a treatment process that uses ultraviolet light to disinfect water or reduce the amount of bacteria present.

• Ultraviolet Treatment Systems have a very high effectiveness in removing protozoa (for example, Cryptosporidium, Giardia);

• Ultraviolet Treatment Systems have a very high effectiveness in removing bacteria (for example, Campylobacter, Salmonella, Shigella, E. coli);

• Ultraviolet Treatment Systems have a high effectiveness in removing viruses (for example, Enteric, Hepatitis A, Norovirus, Rotavirus);

• Ultraviolet Treatment Systems are not effective in removing chemicals.

Water Softeners

• Water Softeners use ion exchange technology for chemical or ion removal to reduce the amount of hardness (calcium, magnesium) in the water; they can also be designed to remove iron and manganese, heavy metals, some radioactivity, nitrates, arsenic, chromium, selenium, and sulfate. They do not protect against protozoa, bacteria, and viruses.

Activated Carbon Filters

• Carbon filtering works by adsorption, in which pollutants in the fluid to be treated are trapped inside the pore structure of a carbon substrate. The substrate is made of many carbon granules or rods, each of which is itself highly porous. As a result, the substrate has a large surface area within which contaminants can be trapped. Activated carbon is typically used in filters, as it has been treated to have a much higher surface area than non-treated carbon. One gram of activated carbon has a surface area over 3,000 m2

• Activated carbon can be highly effective at removing chlorine.

• Carbon block filters are most effective; however, they generally have lower flow rates vs GAC

Please remember that:

• Point of Use (POU) water treatment systems typically treat water in batches and deliver water to a single tap, such as a kitchen sink faucet or an auxiliary faucet.

• Point of Entry (POE) water treatment systems typically treat most of the water entering a residence. Point-of-entry or whole-house systems are usually installed after the water meter and have lower filtration capabilities.

• The treatment technologies described can be used in conjunction with each other for greater pathogen reduction. Adding coagulants, carbon, alum, and iron salts to filtration systems may aid in chemical removal from water.

• Reverse osmosis and ultrafiltration systems offer far superior filtration; slower flow rates generally mean better water.

 

 

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