34 and a branch line 15 the discharge section 13 34 is connected to a shutoff valve 14 which when open enables discharge of liquid into the drain fitting 10 above the valve body 11 via a drain line 62 the branch line 15 is likewise closable with respect to th drain fitting 10 or the drainpipe 3 via a shutoff valve 16 which when open enables discharge of liquid directly to the drainpipe 3 a supply container 17 is provided to supply a cleaning and or disinfecting agent and is connected to the suction line 9 via a shutoff valve 19 and a supply line 18 the overflow line 13 also has a vent fitting 20 preferably extending upwardly as far as the height of the rim of the tub 1 and forming a vent opening for the overflow line 13 branching off from the vent fitting 20 is a transverse line 21 which communicates with the overflow line 4 an automatic valve for instance a float valve 22 is disposed in the vertical section 13 39 of the overflow line 13 at a height above that of the horizontal section 13 34 39 and below that of the transverse line 21 so that only relatively slight quantities of fluid equivalent to leakage can pass from the overflow line 13 into the pipeline 4 via the transverse line 21 the vertical portion 13 39 of the overflow line 13.