FHRSS-11 is required to be used with FUJIFILM water treatment. FHRSS-11 main function is to soften the water coming from the public water source by ion exchange process. Water from Public source is considered "hard-water" due to high content in mineral like calcium and carbonate. Hence to ensure high quality print performance in the FRONTIER machine at all time, the hard-water has to be treated with FHRSS-11.