A vacuum toilet, comprising: - a toilet bowl with a bowl outlet opening, - an intermediate tank with an intermediate tank inlet opening, an intermediate tank outlet opening and a connection for the control air pipe, - a first flow path through a first outlet pipe which connects the bowl outlet opening to the intermediate tank inlet opening of the intermediate tank, - an inlet valve which opens the first flow path in the open position and which closes it in the closed position, - a wastewater tank with a wastewater tank inlet opening which is connected to the intermediate tank outlet opening via a second outlet pipe by means of a second flow path, - an outlet valve which opens the second flow path in an open position and which closes it in a closed position, - a control unit configured to carry out a flushing operation in which, ▪ in a first flushing step, underpressure is generated in the intermediate tank via the connection for the control air pipe and, after underpressure has been generated in the intermediate tank, the inlet valve is switched from the closed position to the open position, ▪ in a subsequent second flushing step, the inlet valve is closed, ▪ in a subsequent third flushing operation, overpressure is generated in the intermediate tank and, after overpressure has been generated in the intermediate tank, the outlet valve is switched from the closed position to the open position, characterised in that the control unit is configured, in a first closure mode, to keep the inlet valve closed and the outlet valve open after the third flushing step, - to keep the inlet valve open and the outlet valve closed, in a second closure mode, and - to alternatingly set the first and the second closure mode within a series of several successive flushing operations. - a toilet bowl with a bowl outlet opening, - an intermediate tank with an intermediate tank inlet opening, an intermediate tank outlet opening and a connection for the control air pipe, - a first flow path through a first outlet pipe which connects the bowl outlet opening to the intermediate tank inlet opening of the intermediate tank, - an inlet valve which opens the first flow path in the open position and which closes it in the closed position, - a wastewater tank with a wastewater tank inlet opening which is connected to the intermediate tank outlet opening via a second outlet pipe by means of a second flow path, - an outlet valve which opens the second flow path in an open position and which closes it in a closed position, - a control unit configured to carry out a flushing operation in which, ▪ in a first flushing step, underpressure is generated in the intermediate tank via the connection for the control air pipe and, after underpressure has been generated in the intermediate tank, the inlet valve is switched from the closed position to the open position, ▪ in a subsequent second flushing step, the inlet valve is closed, ▪ in a subsequent third flushing operation, overpressure is generated in the intermediate tank and, after overpressure has been generated in the intermediate tank, the outlet valve is switched from the closed position to the open position, characterised in that the control unit is configured, in a first closure mode, to keep the inlet valve closed and the outlet valve open after the third flushing step, ▪ in a first flushing step, underpressure is generated in the intermediate tank via the connection for the control air pipe and, after underpressure has been generated in the intermediate tank, the inlet valve is switched from the closed position to the open position, ▪ in a subsequent second flushing step, the inlet valve is closed, ▪ in a subsequent third flushing operation, overpressure is generated in the intermediate tank and, after overpressure has been generated in the intermediate tank, the outlet valve is switched from the closed position to the open position, - to keep the inlet valve open and the outlet valve closed, in a second closure mode, and - to alternatingly set the first and the second closure mode within a series of several successive flushing operations.