Public Works: Floodproofing

When Water Attacks: A Homeowner's Guide to Floodproofing

Part I : Flooding
Part II : Basement problems
Part II.a : Basement Protection Berm
Part III.a : Sewer Backup Prevention - Floor Drain Plug
Part III.b : Sewer Backup Prevention - Standpipe

Part III.c : Sewer Backup Prevention - Overhead Sewer

Sewer Back Prevention - Overhead Sewer
An overhead sewer acts like a standpipe but without the problems. A sump is installed under the basement floor to intercept sewage flowing from basement fixtures and the basement floor drain. An ejector pump in the sump pushes sewage up above the flood level. From there it can drain by gravity into the sewer service line. Plumbing fixtures on the first floor continue to drain by gravity to the service line.

It is unlikely that the sewers will back up above ground level. If water does go higher, a check valve in the pipe from the ejector pump keeps it in the pipes. Backed up sewage is enclosed in the sewer pipes so there is no worry about overflowing laundry tubs or basement toilets.

Precautions
The ejector pump requires maintenance and electricity to work properly. The basement is disrupted during construction. The contractor may have to run the overhead pipes through one or more basement rooms, although often they can be camouflaged. This work requires a licensed plumber and a permit from your building department.

During a power outage, the ejector pump won't work. But this only limits the use of the facilities in the basement that need the pump. The upstairs plumbing still works and the sewer is still prevented from backing up.

Although more dependable than a standpipe, an overhead sewer is more expensive. A plumbing contractor must reconstruct the pipes in the basement and install the ejector pump. It typically costs $2,000-$5,000.

Part III.d : Sewer Backup Prevention - Backup Valve
Part IV : Insurance