Abstract: A plumbing assembly is provided which is formed from a plurality of rigid pipe sections, connected between a movable sink and a relatively fixed fluid outlet. These pipe sections are joined together by swivel fittings that permit the pipe sections to rotate with respect to each other. In this manner, different distances between the sink and the fluid outlet are accommodated by a folding and unfolding motion of the plumbing assembly in a minimum of space behind the wall of an expandable portion of the room. Fluid supply lines for providing hot and cold water to the sink faucet can be mounted within the same spacial area by means of similar swivel fittings that create an offset parallelogram structure. The lengths of at least the fluid draining pipe sections and the supporting structure behind the wall are selected such that a downward slope is maintained over the entire fluid flow path between the sink and the fluid outlet regardless of sink position during usage.