can further be seen from the drawing a floor drainage 8 is formed in the wall element as provided in a bordering floor member 9 in a simple manner so as to be connected with the inner hollows 4 or 5 for this purpose the block members 1 2 and 3 with their inner hollows 4 are so inserted in the floor member 9 that the soles 4a are located below the upper edge of the floor member so that all connections of the object including the floor drainage can be accommodated in any spatial arrangement it can further be seen from the drawing that the mounting of the block members in a structural unit such as in the floor member 9 is performed with the aid of sound absorbing mats 10 the outer walls of the block members are embedded in the sound absorbing mats 10 thus in accordance with the invention the drainage problem for water using units is solved in a very simple manner special pipes of circular cross section are eliminated and any arrangement and dimension of connections for sanitary objects can be provided simultaneously a required descending line or duct can be formed with the aid of the vertical inner hollow 5 the line serving as an upward extending ventilation pipe the individual block members can be easily connected with one another tightly and they can.