The invention concerns a connection device for connecting a first reservoir with a second reservoir, having a first section (11) for arranging the first reservoir (5) closed with a seal (51) a second section (12) for arranging the second reservoir and a piercing element (2) which penetrates with a piercing end (21) the seal (51) of the first reservoir (5) when the first reservoir (5) is arranged at the first section (11). According to the invention, the piercing element (2) can be moved from a first position into a second position, wherein it blocks in the first position a flow connection between the first and the second section (11, 12), while in the second position it allows for a flow connection between the first and the second section (11, 12).
