A method for reliably avoiding backflow in the transport of a liquid under pressure via a transport pipe (1), in which a shut-off device (2) with differential pressure switching is arranged, into a container (3) which is under pressure and which comprises the liquid to be transported and/or another liquid is proposed, wherein a pressure accumulator (4) which is filled with the liquid to be transported up to a certain level and above the liquid level, in direct contact with the liquid to be transported, with an inert gas is arranged in the transport pipe (1) upstream from the shut-off device (2) in the transport direction, the inert gas being provided in the pressure accumulator (4) under an excess pressure and in an amount relative to the container (3) to be filled which are designed so that, in the case of a drop in the pressure in the transport pipe (1), the inert gas ensures a positive pressure difference in the transport pipe (1) to the container (3) over a period which is at least as long as the reaction time of the shut-off device (2) and the shut-off device (2) has an emptying pipe (6) with emptying valve (7).