Evaluated a situation in which a private sewer serving several residences in a court was found to be backing up. The City, which owned the public sewer to which the private sewer connected, inspected their portion of the piping and found that it was not blocked. The City then required the homeowner to replace the private sewer. After construction of the replacement sewer was complete, it was found that it again was not flowing freely. My investigation revealed that the City sewer was not low enough to serve the private sewer and that the system had been built with a sag in it.