The present invention relates to a pump arrangement (1) for a double breast pump (2). The pump arrangement (1) comprises first and second terminals (23, 24) for connecting first and second expression kits (3, 4) having first and second breast shields (5, 6) and at least one container (7) for collecting breast milk (8) in fluidic connection with the expression kits (3, 4), a pump (9) for generating reduced pressure within said breast shields, a plurality of conduits (10, 11, 14, 15, 16), a suction valve (12) connected to the pump (9) by a connection conduit (14) and to the first and second terminals (23, 24) by respective air conduits (10, 11), and a venting valve (13) connected to the first and second terminals (23, 24) by venting conduits (15, 16), wherein the venting valve (13) comprises an opening (17) to the environment. The pump (9) is alternatingly connected to the first and second terminals (23, 24) by alternate opening and closing of the suction valve (12) and the venting valve (13).
