OATEY 43908 6 in. PVC Backwater Valve

Yes. The 43908 is a hub by hub valve sized for 6 in. PVC Schedule 40 pipe, and both hubs are solvent weld sockets, so the pipe goes straight into the socket with primer and cement. No gaskets, no couplings, no threaded adapters needed on the run itself.

The valve hubs are sized for DWV pipe, and Oatey states they can be adapted for sewer and drain pipe. Sewer and drain pipe has a different outside diameter than Sch 40 DWV, so the adaptation happens with a bushing or adapter at the hub, not by forcing S&D into the socket. On a straight DWV line the hubs take the pipe directly.

It stops flow coming back up the line. The 43908 protects low areas and basements from backflow or waste from street sewers, which is the situation where a surcharged municipal main pushes sewage up through the lowest fixture in the building. A spring-free flapper opens for normal outbound drainage and closes against reverse flow.

Yes, and that is the reason to leave access above it. The valve has a threaded access cap with a neoprene seal that can be tightened or removed by hand, so the flapper and the elastomeric seal can be inspected, cleaned, or cleared without tools and without disturbing the solvent welded joints. Set it where the cap stays reachable, under a cleanout cover or in an accessible pit.

It ships as the entire valve assembly, model 43908: body, quick action flapper with its elastomeric seal, and the threaded access cap with neoprene seal. Nothing else to order for the valve itself. You still supply primer, solvent cement, and any adapter needed if you are tying into sewer and drain pipe rather than DWV.

PVC, in white. That matters for the joint: PVC body means PVC solvent cement and PVC primer, and it will not chemically weld to an ABS line. If the existing drain is black ABS, transition with a proper coupling rather than trying to cement dissimilar materials.

For a building drain protecting a basement from street sewer surcharge, a backwater valve like the Oatey 43908 is the part called for: it sits in the horizontal drain line, passes waste and solids outbound through a quick action flapper, and seals on reverse flow. A general purpose check valve is built for pressurized supply or pump discharge and has no hand-removable access cap for clearing debris. On a gravity DWV line carrying solids, use the backwater valve.

About 10.1 pounds for the assembled 6 in. valve, with a shipping volume of 1.217. That is a one-person lift into a trench, but it is heavy enough that on a suspended or underslab setting you want the pipe supported on both sides of the body rather than letting the valve carry the run.