System and method for reusing gray water

A system for reusing gray water contains three containers, namely a collecting container, in the passes the gray water, and in which the water from the collection container in turn is pumped two immediately above the collecting container arranged further. In the first container, a mechanical and / or biological treatment of the gray water is carried out. By controlling the pump that pumps the water into this tank, and the pump, which pumps the water from this tank into the additional container is ensured that the water remains for a predetermined residence time in the container. The residence time is chosen so that the treatment is sufficient to give the water a further attempt to use enabling quality. After expiration of the residence time of the water is pumped into the third container, where it is available for withdrawal as a reusable service water.