Melt-blown Polypropylene Sediment filters – 20" Sediment filter is often the first filter installed in the Whole House Water Filter. Sediment filters are made of fine melted polypropylene, which is then blown and spun in a cylinder-like form. The main function of a sediment filter is to remove large and fine particles from a drinking water, such as sand, dirt, silt, and rust particles. Removal of such particles allows for a better performance of all the following filters, such as Carbon Block or GAC filters.