There are two primary reasons to use pre-filters. The first, and typically most important, is that pre-filters protect the primary filtration media from damage and degradation. Some types of filtration media are susceptible to damage from certain types of contaminants such as chlorine or bacteria. A pre-filter can be installed that is designed to remove those damaging contaminants so that they cannot affect the primary filtration media. In other situations, the pre-filter is used simply to remove some of the larger and easier-to-catch contaminants so that they don’t clog up the primary filter, which extends the primary filter media’s life.

The second reason pre-filters are used is to remove contaminants that the primary filter is unable to catch. This allows the water system as a whole to remove a wider range of contaminants and produce better quality water than you would get by using the primary filter on its own.