A service pipe shall be installed for each dwelling or commercial enterprise adjacent to the water system. Each dwelling or commercial occupancy shall have a separate connection to the system, regardless of whether or not the dwelling or commercial occupancies 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 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 connections.