The preparation of functionalized filter media (FFM), its ability to release active antiscalant substances and its application for water treatment in water heating processes and as a pretreatment in reverse osmosis (RO) desalination were investigated in this study. FFM is a novel method of stabilizing water pretreatment designed to be free of the disadvantages of conventional methods of water scaling potential reduction which require expensive equipment, produce significant amounts of waste, have high reagent consumption or are strongly dependent on water composition. FFM was derived from anion exchange resin modified with phosphonate and polymer scale inhibitors. In order to choose the most suitable anion exchange resin for preparation of FFM, different types of resins were tested for sorption of phosphonate compounds. The effect of the anionic composition of water and the effect of the polymer inhibitor on the rate of phosphonate release were investigated. Finally, FFM was tested as a scaling reduction water treatment for a water heating process with heating coils and as a pretreatment before reaching the RO unit. In both cases the results obtained show great promise for the functionalized material in antiscaling water pretreatment.