What is a Backwater Valve?
It allows the water from sinks, toilets and tubs in your home to flow into the sewer system while blocking the sewer system from flowing back up into the home. The backwater valve has a flap that shuts close if the sewer system should start to back up and flow back into the home’s pipes.
Although a backwater valve is a fairly simple device in construction and design, it can be a complex undertaking to understand how they operate. As part of the name states, the device is a valve and therefore can be closed or opened. The closing and opening of the gate, or flap as it’s sometimes called, is controlled by floats below the gate which cause the gate to lift and close to stop the backflow of water as the level of water in the valve raises in the sanitary sewer line. As the level of water flowing from the sewer line increases, the gate is lifted further and the pressure increases, creating a seal between the gate and the gasket, therefore blocking the sewer water from flowing into the home’s pipes and plumbing. Once the level of the sewer line’s water recedes back to a normal level, the gate falls back down and opens the valve.
There are a couple types of backwater valves. Although we won’t go into detail and bore you with each type, the main difference is where the device is installed. The most common type is installed inside the home or business by cutting a hole in the foundation above the main sewer line. It’s known as a mainline full port backwater valve. The other less common type can be installed outside of the home on the sewer line, like in the homeowner’s yard.
