Abstract: An apparatus for electrical treatment of water can be used for purifying and disinfecting potable water, and also for producing detergent and disinfecting solutions, and comprises at least one electrochemical cell made up of an upright cylindrical electrode and a rod electrode of a variable cross-section mounted coaxially in dielectric sleeves, an ultrafiltration diaphragm made from ceramics based on zirconium oxide and coaxially mounted in the sleeves between the electrodes, the geometrical dimensions of the cell meet some definite relationships. The system of openings in the electrodes and ducts in the sleeves provides for the optimal hydraulic characteristics of the cell. The sleeves and cylindrical electrode have the same external diameter and the cells are specially secured by means of gaskets in the upper and lower headers of a dielectric material with cylindrical sockets in each and supply and discharge ducts.