The invention relates to a process for treating an alcoholic feedstock, comprising: a) a stage of preheating of said alcoholic feedstock to a temperature of between 70° C. and 200° C.; b) a stage of pretreatment on an acidic solid, operating at a temperature of between 70° C. and 200° C., to produce a pretreated alcoholic feedstock; c) a stage of partial vaporization to produce a vaporized stream and a liquid stream; and d) a stage of purification of the liquid stream resulting from stage c), to give a stream rich in water, a stream rich in monoalcohol and a stream rich in impurities.