Results of treatment of groundwater with the increased content of iron, silicon and high permanganate oxidizability are presented. A novel technique of deferrization and desiliconization on the basis of the coagulation and oxidation processes is proposed. In the process water is to be treated simultaneously with a coagulant (aluminum polyoxychloride) and an oxidizer (potassium permanganate) then it is to be filtered on a grained bed. It has been stated that the optimal Al/KMnO4 proportion is to be equal to 10. Concurrent processing with a coagulant and an oxidizer enables to dispose effectively iron with organic matter. The proposed technique can be recommended for simultaneous deferrization and desiliconization of groundwater with permanganate oxidizability exceeding 5 mgO2/l.