Emergency Sewer Repair

Stop using every drain immediately, because everything that goes down adds to what is coming up. Keep people and pets away from the affected area and treat it as a health hazard rather than a mess: waste water carries bacteria and it contaminates anything porous it touches. Do not attempt to plunge a main line backup, which tends to push waste further into the property. Then call, and say that sewage is entering the building, because that changes the priority of the visit.

It depends where the defect is, and a camera run is what settles it. In most places the lateral from your house to the connection at the public main is yours to maintain, including the section under the sidewalk, while the main itself belongs to the city. If the camera shows the blockage or collapse is at or beyond that connection, it is the city's to fix, and having the recording makes that conversation much shorter.

Cleared, sometimes. Repaired, almost never, and you should be wary of anyone who says otherwise. A collapse needs excavation or trenchless work, which needs utility locating so gas and electricity are marked, a permit, and an inspection. What can happen overnight is containment and, where the pipe still holds enough shape, enough clearing to make the property usable until the proper repair is scheduled.

That points at water getting into the system rather than at a blockage in your line. Either the public sewer is surcharging because it is taking more than it was sized for, or your own lateral has cracks and open joints letting groundwater in. The two need different fixes: a backwater valve protects the house when the public system pushes back, while lining or replacing the lateral stops infiltration at source. A camera during dry weather distinguishes them.