Basement Backflow Prevention Program

In some older parts of MSD's service area, water from combined sanitary and storm sewers backs up into basements during heavy rains.

In 1994, MSD started a program to help owners of some of these homes to install backflow prevention devices at MSD's expense.  For the first few years, MSD offered the program to about 450 property owners per month.  After the March 1997 flood, MSD began offering it to any residential sanitary sewer customer reporting a backup and notified customers in areas where backups were reported that they were eligible for the program. The program continues to be available to all MSD customers experiencing sewer backup.

The two most common installations are a sump pump or a backwater and ball valve. The following are brief descriptions of how these installations work.

If there is a floor drain in the basement but no toilet or shower, a sump pump will be installed. Most likely the floor drain is connected to the main sewer in the street. Therefore, the floor drain is the first place the main sewer could back up into the basement. The sump pump installation consists of capping the existing floor drain, installing a sump pump, and then installing a new floor drain that will be connected to the sump pump. By capping the existing floor drain the main sewer can no longer back up into the basement. The new floor drain runs into the new sump pump that discharges outside. Usually only a small amount of clean water runs into the floor drain so the amount of water discharged by the sump will be small also.

If there is a toilet and/or shower in the basement a backwater valve and a ball valve will be installed. The valve installation consists of placing a backwater and ball valve in the basement between the toilet and floor drain and the main sewer in the street. If the main sewer backs up into the house the backwater and ball valve will prevent the water from getting to an outlet (the toilet, shower or floor drain) and causing basement flooding.

This is only a brief description of installation types. All homes are different and individual installations vary. To find out more, call MSD Customer Service at 587-0603 and request a Basement Backflow Prevention Program information packet.

For more information, please contact:  Martin Schindler

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