All pollutants dissolved or existed in water can be grossly classified as ionized and neutral species. The former includes inorganic and organic ions, while the latter contains inorganic molecules, organic molecules and organisms. Using flow through capacitor for performing capacitive deionization (CDI), the ionic contaminants can be effectively and economically removed from water. Whereas the neutral contaminants are not retained in the static electric field of CDI, they can be decomposed upon flowing through an electrolytic ozonator. Either gaseous or ionic products will be generated at the ozone treatment, and the ionic byproducts can be subsequently removed by CDI. By integrating the electrolytic ozone reactor with flow through capacitor, the O.sub.3/CDI hybrid technique becomes a total solution for eliminating hazardous materials in water. Both the reactor of in-situ ozone and the flow-through capacitor (FTC) of CDI are operated in energy conservative and pollution free conditions, so the detoxification of water is highly cost effective.