You should not need to replace the sponge at the base of the HS-72's Machine's pitcher. Just keep it clean, or if it gets soiled, it can be cleaned as you would any sponge. [Note: I clean my sponges in the top rack of the dish washer]. If your sponge gets lost or damaged beyond repair somehow, this is the replacement for it. You cannot operate the HS-72 Machine properly without this sponge, and no other substitute sponge will do.