Sewage Smell in the House: 6 Sources and How to Find Yours
A sewage smell in the house is unpleasant, and sewer gas contains methane and hydrogen sulfide, so it is worth finding the source rather than lighting a candle. The smell almost always comes from one of six places.
The six usual suspects
1. A dry P-trap. Every drain has a U-shaped trap that holds water to block sewer gas. A guest bathroom, basement floor drain or laundry sink that has not been used in weeks lets the water evaporate. Run water for a minute; if the smell fades, that was it.
2. A failed toilet wax ring. If the smell is strongest around a toilet, especially one that rocks slightly, the wax seal under it has failed. That is a quick toilet repair.
3. A blocked or cracked vent stack. Plumbing vents let gas out through the roof. A bird's nest or a crack in the attic can push gas back into the house, often with gurgling drains.
4. Biofilm in a drain. A smell from one sink or shower drain that is otherwise draining fine is usually bacteria in the overflow or trap. A thorough drain cleaning fixes it.
5. A failed sewage ejector or sump pit seal. Basement bathrooms use an ejector pump in a sealed pit. A cracked lid or failed gasket leaks gas. See sump and ejector pump service.
6. A broken sewer line under or near the house. If the smell is in the basement or yard, drains are slow, and the lawn has a suspiciously lush strip, the lateral is likely cracked. A sewer camera inspection confirms it.
How we track it down
We start with the cheap causes (traps, wax rings), then smoke-test the drain and vent system if needed. Smoke shows exactly where gas is escaping. Most Milford homes get a definitive answer in one visit.
Related service: Sewer Line Repair · Sewer Line Repair in Milford