To prevent this, have a licensed plumber install an interior or exterior backflow valve.
To prevent this, have a qualified, licensed plumber install an interior or exterior backflow valve.
One way to prevent sewage from backing up at these locations is to install a backflow valve on a the lowest drain.
To help prevent this, install a backflow valve in the sewer line.
At a minimum, an automatic backflow valve should be installed to prevent sewage from backing up into the building during flooding.