Clean-outs and back-water valves are the resident’s key to keeping the private sewer service in good working condition and protecting the home from sewer back-up problems.
A clean-out is a vertical pipe that provides access to a property’s sewer service, allowing homeowners or plumbers to clear blockages that disrupt service. A clean-out cap is typically white PVC or metal, about 4 inches in diameter, and located near buildings.
Both homeowners and tenants should locate and inspect their clean-out cap before a plumbing emergency occurs. Keeping the caps screwed onto the clean-out helps prevent possible sewer backups caused by yard debris, dirt, and other items entering the sewer system. Capping also stops excessive inflow and infiltration, which can overload the system and cause overflows.
A back-water valve is the resident’s protection against sewer back-up into the structure. If water tries to back up from the sewer mainline, the valve prevents sewage from backing up into the building. Back-water valves are typically located either outside near the building or in a floor drain in a basement. Those outside have a cap similar to a clean-out cap and a vertical pipe down to the valve. Size and maintenance needed depend upon the manufacturer of the back-water valve.
You can protect yourself from sewer problems by making sure you have an accessible clean-out, keeping your sewer line in good condition, and by making sure you have a functional back-water valve.
The photo below shows a back-water valve with 2 clean-outs. The caps have been removed to show how the back-water valve allows fluid to flow in only one direction.
Back-water valve with 2 clean-outs