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Option 15: Mainline, normally open backwater valve

The proper installation of a mainline backwater valve can be complicated. In an existing home, installation will require breaking up the concrete basement floor and cutting a section out of the sanitary sewer lateral. You will need the assistance of a licensed plumber to install a mainline backwater valve. Talk to your municipal government to see if they have a list of pre-approved plumbers who can install backwater valves.

Like any other part of the home, backwater valves require periodic maintenance to ensure proper performance over time. An improperly maintained valve may fail during a flood event. Most mainline backwater valves come with a see-through top so that you can check to see if it is clogged with debris. The valve should be checked regularly to ensure that it will function properly when it is needed. You will likely need the help of a qualified plumber to carry out maintenance of the valve.

In order to drain your foundation drain when the backwater valve is closed, you should also disconnect your weeping tile from the sanitary sewer, which will require the installation of a sump-pump and sump-pit (see Option 14). If weeping tiles are connected to the sanitary lateral, weeping tile drainage may backup into the basement when the backwater valve is closed, as this water will have no other way out of the home. Disconnecting the weeping tile from the sanitary sewer lateral will also reduce the chances that water will backup into the weeping tile and cause structural damage and infiltration flooding in the home.

For proper operation of the backwater valve, sewer cleanout ports must be properly capped and sealed. The placement of the sewer

cleanout relative to the backwater valve will vary depending on the

nature of the home’s plumbing system.