Abstract: A process for the treatment of water in which at least a partial flow of the water is brought into contact under pressure in a packed column with an ozone-oxygen mixture from an ozonizer with the ozone and a portion of the oxygen being dissolved in the water and the undissolved oxygen being returned to the ozonizer and with the charged water being withdrawn from the column, includes branching off a partial flow from the column water to a water jet-gas compressor in which the ozone-oxygen mixture from the ozonizer is adsorbed and compresed and mixed with the partial flow after which the mixture of water, ozone and oxygen is led into the base of the packed column.