Abstract: Water intended for injection into an oil reservoir is freed from oxygen by gravitating the water through a vacuum tower. Gases liberated from the water by the vacuum process are drawn off at the bottom of the respective stages of the tower. Liberated nitrogen at the top of each stage will then flow down through the tower in cocurrent flow with the water and thus act as an internal stripping gas reducing the partial pressure of oxygen in the gaseous phase. Gases and vapors drawn off from the bottom of each vacuum stage after the first stage are pressurized to the pressure of the preceeding stage and reinjected into that stage.