Cold plasma technology has been the hot topic study for water treatment in recent years. This technology is efficient, non-chemical and environmentally friendly. This study will compare this technology to other conventional methods, i.e. chlorination, ozonation and UV. The method to generate cold plasma from dielectric barrier discharges is presented. Cold plasma efficiently destroys or inactivates bacteria. Furthermore, plasma can oxidize organic compounds and inorganic pollutants in water. A model of water treatment by cold plasma is introduced and will be investigated. Some first results are achieved. The breakdown characteristics of the plasma chamber are examined. Dielectric strength of air is about 1-1.5 kVrms/mm while the surface dielectric strength of glass tube in air is only 0.4-0.5 kVrms/mm. With the applied voltage of 9-12 kVrms, plasma will appear in the air gap of 5 mm.