Filter Quality

Filter Quality

1. What is inside a refrigerator water filter?

The typical water filter medium is activated carbon. There are two different types of activated carbon used in filters: granular activated carbon (GAC) or carbon blocks. Filter-Outlet does not sell filters containing recycled (chemically washed) activated carbon.

2. What is activated carbon?

Activated carbon is carbon which has an electro-positive charge added to it, making it even more attractive to chemicals and impurities. As the water passes over the positively charged carbon surface, the negative ions of the contaminants are drawn to the surface of the carbon. This process is called catalytic reduction.

3. How does the water filter work?

There are two principal mechanisms by which activated carbon removes contaminants from water; adsorption and catalytic reduction.
Adsorption: involves the accumulation of molecules on the surface of a material, in this case activated carbon.
Catalytic reduction is a process involving the attraction of negatively-charged contaminant ions to the positively-charged activated carbon.
Organic compounds are removed by adsorption and residual disinfectants such as chlorine and chloramines are removed by catalytic reduction.

4. Which is generally better, GAC or carbon block?

Although both are very effective, carbon block filters generally have a higher contaminant removal ratio and are more resistant to channelling.

5. Are all carbon filters equally effective?

No. Activated carbon filters are usually rated by the size of particles they are able to remove, measured in microns, and generally range from 50 microns (least effective) down to 0.5 microns (most effective). The two most important factors affecting the efficiency of activated carbon filtration are the amount of activated carbon in the unit and the amount of time the contaminant spends in contact with it. In general, a greater mass of quality carbon will result in better filtration. 

The most common carbon types used in water filtration are bituminous, wood, and coconut shell. While the coconut shell carbon typically costs more, it is by far the best for fresh tasting water. Filter-Outlet does not sell filters containing recycled (chemically washed) activated carbon.

All our Original water filters are genuine. All our Replacement water filters are either manufactured in the USA / Europe, or South Korea. Buy fridge filters always states the country of manufacture.