The invention relates to a liquid supply interface for a cell culture system for supplying cell cultures found in different cell culture containers with a nutrient medium, wherein the liquid supply interface comprises: a housing defining a flow area; a first connection formation for the liquid-transferring connection of a first fluid line to the housing; a second connection formation formed separately from the first for the liquid-transferring connection of a second fluid line to the housing; a third connection formation formed separately from the first two for the liquid-transferring connection of the housing to a third fluid line; a coupling formation formed separately from the connection formations, which is formed for the producible and detachable liquid-transferring coupling contact according to the operation, with a corresponding counter-coupling formation of a cell culture container.