Abstract: An apparatus for disinfecting a continuous flow of an electrically conductive liquid such as water which is contaminated by cells of microorganisms. The apparatus consists of a container through which liquid to be disinfected flows, and at least one pair of non-sacrificial electrodes which are positioned in the container so that liquid flowing through the container is in contact with the electrodes. A steady state electric voltage is applied across the electrodes so as to create a voltage gradient between them, the voltage gradient being such that an arc is not struck between the electrodes but a voltage gradient of at least one volt is produced across the membrane of any cell in the liquid, thereby causing dielectric breakdown of the cell membrane and electropermeabilization of the membrane.