The invention relates to a liquid supply system wherein liquid, such as for example, a supply of warm water, circulates. Said system consists of thick outer tubes, the inner chamber of said thick outer tubes allowing a liquid to flow through, a thin inner tube is respectively placed inside the outer tube in which the liquid can flow in the direction counter to that in the inner chamber. In the path of at least one outer tube, a first tube branch is introduced enabling the first inner tube to be withdrawn, and in said first branch, at least one functional component, such as a shut-off valve, is introduced into the inner tube and guided to a second tube branch in the path of an outer tube and extends further through said tube branch and then into the inner chamber of the latter outer tube.