A siphon trap disinfection unit consisting of a copper/silver electrode coated on inside body of the siphon parallel to each other along the siphon in the area which water normally stands. A water level sensor to generate resistance between two electrodes and an electric controller circuit to generate ions by applying voltage between two electrodes and controlling the amount of current passing through this control circuit to generate enough concentration of copper and silver ion continuously in the water standing area of the siphon trap to remove and deactivate harmful bacterias in this area.