There are a couple different types of backwater sanitary valves, and they are installed in different ways. The most commonly used variety is called a Mainline Full-port Backwater Valve, as shown in the image to the right (courtesy Multi-Drain Inc.). It is installed by cutting a hole in the foundation inside the home above the main sewer line to expose it and allow for the installation of the device. There is another less common variety that can be installed somewhere on the sewer lateral outside the house, in the lawn for example.

No. Unfortunately, while they can offer a lot of protection, there is no guarantee that a sewage backup will not occur because of a number of factors:

Because there are a number of code requirements pertaining to backwater sanitary valves, a plumbing permit is required for installation. A plumbing inspection will allow for confirmation that the contractor has installed it correctly. A note of caution: while contractors are aware of this, they do not always acquire a permit or even inform you that one is required.

A backwater sanitary valve is a type of check valve that is designed to only allow flow in one direction. Different backwater sanitary valves work in different ways, but in general, the type of device that is used in sanitary sewer scenarios works like this:

The location of installation needs to be downstream of all fixtures to offer full protection, in addition to any other manufacturer's requirements that may exist. Installation of a backflow prevention device is not simple and this work is best undertaken by a licensed and qualified plumber, and it does require a Plumbing Permit from the City. Knowing if your foundation drain goes to the sanitary sewer or not is critical, and ideally, it should be redirected.

The City is offering residents a financial subsidy to install a backwater valve. For more information and to see if you qualify, visit our Basement Flooding Protection Subsidy Program (BFP) page.

Office of the City Engineer350 City Hall Square West, Suite 210Windsor, OntarioCanadaHours of Operation: 8:30 a.m. to 4:30 p.m. Monday to Friday (excluding holidays)