A device for antibacterially treating, in particular decontaminating and/or sterilizing water and for killing microorganisms in water, which device is developed to work together with a container designed for holding a quantity of water intended for treatment, and has an electrode arrangement set up for pulsing the quantity of water in the container, the electrode arrangement being connectable to and operable with an electrical signal-generating device, and the device having a discoid housing, which is preferably provided in the container in detachable or removable form, and having the electrode arrangement on at least one flat outer side of the housing, and the electrical signal-generating device in the interior of the housing.