Storage containers (4, 14) located in a first supply station (1) are provided for mixed constituents which are characteristic of a first product. Outflow lines (8, 18) which can be closed run out of the storage containers (4, 14) via first closing devices (61, 62). A second set of storage containers (24, 34) located in a second supply station (2) are provided for mixed constituents which are characteristic of an additional product. Second outflow lines (48, 58, 68) which can be closed run out of the second set of storage containers (24, 34) via second closing devices (63, 70). Storage containers (44, 54, 64) located in the third supply station (3) are provided for mixed constituents which are available in both products to be produced. Outflow lines (48, 58, 68) are permanently open when the system is in operation. The first outflow lines (8, 18) communicate with the outflow lines (48, 58, 68) of the third supply station (3) via a transport line (20) having a stop valve (21). The additional outflow lines (28, 38) communicate with the outflow lines of the third supply station (3) via a transport line (22) having a second stop valve (23).