The replacement filters are divided into four main categories:
- Mechanical that removes contaminants from water with different size screenings indicated by micrometers.
- Absorbent whose activity is based on the ability of filtering mass to bind impurity to itself.
- Ion exchange, whose function is based on the phenomenon where, as the impurity passes through the filter mass, its composition becomes a second harmless compound.
- For oxidizing or reducing, in which the pass filter through the filter is changed so that its adverse effects are already neutralized in the filter.