What Does a Sewer Smell in My House Mean?

A sewer smell often starts with a dried-out P-trap. Every sink, shower, and floor drain has a curved trap that holds water to block sewer gas. If a drain goes unused for weeks, that water evaporates and gas slips through. Run water in every drain monthly to keep the seal intact.

Another frequent cause is a cracked or loose vent pipe. Plumbing vents run through your walls and roof to release gas outside. When they break, gas can leak into living spaces. A broken wax ring around a toilet base is also a common source, letting odor seep out from the floor line.

Start by checking the obvious spots. Sniff around each sink, toilet, floor drain, and washing machine standpipe. Listen for a hissing sound near pipes, which could indicate a leak. Lift the lid on your cleanout access point if you have one, but do not open it if it is full or under pressure.

Pour water into any drain that has not been used recently. If the smell disappears, the trap was the culprit. If it persists, inspect the toilet base for a damaged wax ring by checking for water stains or wobble. For a gas water heater, confirm the vent is connected and not corroded.

Run water in every sink, shower, and floor drain at least once a month. This keeps the P-traps full and the seals working. For floor drains, pour a cup of water down them seasonally, since they are easy to forget. If a drain is rarely used, consider a drain seal or a plug.

Have your plumbing vents inspected during any home maintenance check. Roof vent pipes can get damaged by wind, debris, or age, especially in coastal climates with frequent storms. Also, avoid pouring grease or heavy solids down drains, which can cause blockages that lead to pressure and gas backups.