An apparatus and method for improving the operation of sewer systems includes a first set of sewer lines connected to a source of other water and a second set of sewer lines of smaller diameter than the first sewer lines connected to sources of sanitary effluent, the first and second sets of lines being separately connected to a sewerage treatment plant. The second set of sewer lines can be attached to the interior surfaces of the first set of sewer lines by an adhesive material and fasteners. A liner can be provided in the first sewer lines with the second sewer lines being positioned between an exterior surface of the liner and the interior surface of second sewer lines.