Abstract: A process for the continuous production of boiler feed water from process waters in the oil extraction industry during which salts and hydrocarbons are removed from the water, without Fe.sup.++ precipitating. The heavy hydrocarbons are mechanically separated, the volatile hydrocarbons are separated from the water, by means of a thermal degassing, and the low boiling and the non-condensable hydrocarbons are separated in a shower evaporation step with downstream vapor compression, wherein the low boiling non-condensable hydrocarbons are evaporated with the waste water within the shower evaporator and the non-condensable hydrocarbons then are drawn off from a downstream separator. A salt-free oxygen-free pure water is removed from a separator.