Dishwashing machine

Dishwashing machine including an outer casing with an inner washing cavity adapted to accommodating a dishwasher rack. A catchment sink assembly is located on the bottom of the inner washing cavity to collect and accumulate liquid trickling down from the dishwasher rack momentarily located above the catchment sink assembly. The catchment sink assembly includes a basin-shaped catchment tank. A cup-shaped drain sump extends downwards from the bottom of the catchment tank and directly communicates with the inside of the catchment tank to receive washing or rinsing liquid arriving on the bottom of the catchment tank. A tubular member communicates with the catchment tank and is detachably fitted into a corresponding tubular outlet portion in the drain sump to divide the inner volume of the drain sump into a first inner-volume portion directly connected to a water drain line, and a second inner-volume portion directly connected to the suction of the pump.