There was proposed method of toxic water soluble substances with low concentrations from very large volume of water using suspended ultradisperse magnetocontrollable sorbents. Suspension of particles of magnetocontrollable sorbents mixed with contaminated water. Due to small size and density close to the density of water, the sorbent particles can be a longtime in the water column, carrying out absorption of pollution. Then sorbent particles with absorbed contaminant removed by magnetic or cyclone separation. For natural water bodies (rivers, lakes) magnetic separation seems preferable, since allows the sorbent to remove magnetic particles without removing the natural particles suspended in water (silt, plankton and other non-ferromagnetic impurities). There was proposed design of magnetic separators suitable for very much volume of water and how to use them. There were considered particles types of magnetocontrollable sorbent, applicable for this method. The most promising particles tested in model systems.