The present invention relates to a portable device for generating ozone in water, purifying the water and making it drinkable. The device comprises a housing; at least two electrodes, including an anode and a cathode extending from the housing into the water and each having semi-rough or rough surfaces in contact with the water. The device also comprises a power supply operatively connected to the electrodes for generating between them a difference of potential creating a current and the hydrolysis of the water creating ozone that purifies the water. The electrodes may have a plate or a rode and tube configuration with a plurality of holes with rough edges. The roughness of the surfaces and of the edges of the holes leads to a coalescence of tiny hydrogen bubbles into larger hydrogen bubbles. The hydrogen may be also removed by absorption in a conductive material and regenerated for reuse.