The paper deals with a new import-substituting antiscalant to protect reverse osmosis membranes of water desalination systems in Uzbekistan. The studies show that during the purification of natural brackish waters typical for Uzbekistan, the reverse osmosis membrane is contaminated by mineral salts and colloidal particles, which leads to the reduction of the membrane capacity and service life of expensive reverse osmosis water treatment systems. The developed import-substituting antiscalant has proved to prevent the sedimentation process on membranes, and to have technical specifications almost identical to its more expensive foreign analogues. Since 2020 water desalination systems using the new antiscalant have been widely used in Uzbekistan to provide the population of the Republic with high-quality drinking water.