Adapter for coupling two connecting pipes

An adapter that is used for connecting pipelines of a system for liquids installed internally in an aircraft and for floor-bridging installation in an aircraft is improved to such an extent that the adapter arrangement is carried out with less labour and fewer difficulties being experienced in the installation. Preinstallation of the adapter on floor panels implement leakage-free (non-dripping and pressure-proof) connecting pipes The connecting pipes are integrated in an aircraft's internal system for liquids and are separately laid out in the interior of the aircraft, above and/or below a floor. The adapter comprises an adapter top and an adapter bottom, which are both implemented with a pipe-shaped adapter body. The latter is intended for connection to the aircraft's internal system for liquids, such as potable water or waste water. The adapter bottom comprises a first pipe that can be positioned within a recess in the floor. An attachment flange is formed to the external circumference of the first pipe, which adapter flange is attached to a lower floor region of the floor. The adapter top may comprise a pipe connection piece which can be inserted into the pipe cross section of the first pipe, wherein the external circumference of the pipe connection piece is connected, by joining, to the internal pipe wall region of the first pipe.