A sewer backup can occur as a result of a blockage in the sewer main or service.  The cause of a blockage can result from separated joints, clogged pipes, root damage, or cracked pipes.  When sewage overflows from the toilet, tub, sink or any drain in your home and the flow is intermittent, the blockage is most likely in the service line.  A steady, continuous flow from a back-up is more indicative of a possible blockage in the sewer main.  The District performs high-pressure cleaning and closed-circuit television (CCTV) inspections as part of a scheduled preventative maintenance program to help prevent main line back-ups.

Since the property owner is responsible for the service line blockages, a list of items you should avoid flushing or putting down the drain as well as other vital information to protecting your home from damage as a result of a sewer backup is available here.