A batch dishwasher (1) has a treatment chamber (2) with at least one wash system which is designed as a recirculation system, wherein the treatment chamber (2) has at least two treatment zones (6, 7) in which washware can be treated at the same time but independently of one another, in particular independently of one another in respect of action time, wash and/or rinse mechanics, and/or independently in respect of the selected treatment program. The at least two treatment zones (6, 7) are each realized in such a way that at least one dish rack (5) can be inserted and removed, and wherein the dishwasher (1) has a mechanism for retracting or extending a dish rack (5) into at least one and, respectively, out of at least one of the at least two treatment zones (6, 7) as required.