Abstract: A method and an apparatus for electrolyzing water in which electrolysis of water can be carried out while effectively removing scales such as calcium carbonate and by which the service life of electrode can be extended on the order of several years. Repeated in sequence are a step wherein water is subjected to electrolysis while using an electrolytic cell of the membraneless type and a step wherein feed of water through the cell is stopped and an electric potential of reverse polarity is applied between electrodes while water stays stagnant in the cell whereby precipitate deposited on the electrodes during the electrolyzing step is removed by dissolving into stagnant water. Since application of the reverse potential is effected while water stays stagnant in the cell, the surface of the electrodes is free from the influence of turbulence and there is no risk that a layer of strongly acidic water generated at the surface of the electrodes is washed away by water flow.

Abstract: An electrolyzer for producing alkaline and/or acidic water by way of electrolysis of water. The electrolyzer (36) comprises a pair of planar electrodes (98; 100; 102) which are arranged opposite to each other without intervening a membrane therebetween. To remove scale such as calcium carbonate deposited during electrolysis on the electrodes (98; 100; 102), an electric potential of a reversed polarity is applied to the electrodes everyday at night and/or at the time when water is fed for the first time in the morning of the following day. During use of the electrolytic cell, the duration of electrolysis in the alkaline water supply mode and the duration of electrolysis in the acidic water supply mode, with a limit of maximum 30 seconds, are cumulated in a countervailing manner. For descaling, an electric potential of the polarity opposite to the polarity of the mode which is operated for a longer period of time is applied to the electrodes.