A house connection shall be installed for each dwelling adjacent to the sanitary sewerage system. Each dwelling shall have a separate connection to the system regardless of whether or not the dwellings are owned by one person. Multiple dwellings shall have separate connections for each dwelling unit except where this would create a manifest hardship, in which case the Public Service Director may grant special written permission to the owner to use a single connection. Commercial establishments shall have separate connections to the system regardless of whether or not these occupy a single structure. No permit shall be issued which contemplates the construction or installation of any multiple use connection.