A sewer odor inside the house can have several plumbing-related causes. In this video, Grant describes three places a plumber may investigate: drain traps, the seal beneath a toilet, and the plumbing vent system.
A drain trap may have dried out
Grant explains that a trap holds water to help prevent sewer gases from entering the home. In a seldom-used utility sink or floor drain, that water can dry out, allowing odors to pass through.
He describes occasionally adding water to an infrequently used floor drain to keep its trap filled. If a dry trap appears to be the source, restoring that water barrier may address the odor. An odor that remains or returns still needs investigation.
The toilet seal may have failed
Another possibility is the wax seal at the toilet’s connection to the drain. Grant notes that a toilet that has been replaced or moved may have a seal that is no longer seated correctly. That can provide a route for sewer odors to enter the room.
A plumbing vent may be blocked
Grant also describes obstructions in plumbing vents, which commonly extend through the roof. He has encountered bird nests and even vents accidentally covered during roofing work. These vents serve the drainage system; they are not simply bathroom exhaust fans.
Get help when the cause is not clear
These examples are possible causes, not a diagnosis based on smell alone. Grant recommends contacting a plumber if you cannot identify the problem quickly. Ask Darnold & Lyons to investigate a persistent or unexplained sewer odor rather than repeatedly masking it.
