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

Sewer Backup Prevention - Standpipe
A standpipe is an inexpensive alternative to a floor drain plug. A "donut" with metal end pieces and a rubber gasket in the middle is placed in the floor drain. A length of pipe is placed in the "donut hole." Bolts are tightened and the metal end pieces squeeze the gasket to make a tight seal on both the floor drain and the pipe. The "donut" can be purchased for about $10. A three-foot length of pipe costs less than $5.

When the sewer backs up, the water stays in the pipe. Water pressure cannot build up to blow a standpipe (if properly installed) out of the floor drain. The system works unless the backup is so deep that it goes over the top of the pipe. One advantage of the standpipe over the floor drain plug is that the overflow acts as a safety valve. Flooding the basement equalizes water pressure on the walls and floor, minimizing the chance of a cracked floor from broken pipes underneath.

Precautions
A standpipe left in the floor drain may contribute to a wet basement if spillage cannot drain out. A standpipe only protects up to its height, normally three feet. Deeper flooding will flow over the parent. (A taller standpipe is not recommended because it can result in too much water pressure on your pipes.)

A standpipe does not stop backup from coming out of the next lower opening, such as a laundry tub or toilet in the basement. Sealing the base of the toilet to the floor will protect you until the water backs up higher than the top of the bowl.

Because water pressure depends on the height of the water in the pipes, a standpipe does not reduce the pressure in the pipes. Because the pressure in the pipes is the same with a standpipe or a plug, standpipes and plugs are only recommended for building with cast iron sewer lines underneath the floor.

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