A separate and independent building service sewer shall be provided for every building. However, where one building stands at the rear of another on any interior lot and no private sewer is available or can be constructed to the rear building through an adjoining alley, courtyard or driveway, the building service sewer from the front building may be extended to the rear building and the whole considered as one building service sewer.
(2005 Code, § 102.11)