“Normally Closed” backwater valves are required by the building/plumbing code to protect plumbing fixtures below grade from “back surges” of sewage into the structure due to flooding or sewer line damage. Often, the placement of the backwater valve can cause accessibility problems for the homeowner when servicing or cleaning is required and if extra branchlines are installed, extra backwater valves and associated fittings are required, resulting in extra costs.


The Mainline Fullport Backwater Valve initiated a special change to the National Plumbing Code ( NPC 95 ) which now permits “Normally Open” backwater valves to be installed on the main building drain in Canada eliminating the need for branchline backwater valves and main sewer cleanouts. The Mainline Fullport Backwater Valve allows regular sewage flow from the inlet to the outlet side of the valve with no flow restriction. It has built-in flow channels, which direct the sewage through the valve to prevent sewage flow beneath the gate. This valve is also fitted with stop points at the wing area, as well as a wall which the gate sits on, to protect the hinge area beneath the gate from contamination of sewage.


Upon reversal, the back surge is diverted to the 45-degree wings on the gate causing an upward lifting action. Once the lift occurs, the flow of water slams the gate into the closed position, protecting the entire plumbing system from municipal sewage back surge. The gate has also polyethelene foam inserts which will float the gate into the closed position in a slow reversal of sewage back surge. The floatation devices are CSA approved for this use.


The Mainline Fullport Backwater Valve also has a built-in cleanout for the rodding and cleaning of the main building drain sewer. We also offer the MAINLINE ACCESS BOX for installation of the back- water valve. This unit provides for easy access for cleaning and is large enough to accommodate water service lines along side the valve. Mainline… designed with the end user and installer in mind!


For complete product offering, visit their website here.