Homeowner library · Drains
Sewer smells in the house
A sewer smell inside means sewer gas is escaping somewhere. Most causes are simple to find and fix.
- Smell near floor drain
- Smell at toilet base
- Gurgling drains
- Smell in a rarely used bathroom
- Licensed, insured trade work (details confirmed when you call)
- Diagnosis before anything is cut
- Emergency calls taken
- Etobicoke and the west end
Dry traps
Floor drains and unused fixtures lose the water in their traps through evaporation, letting gas through. Pour water into them regularly.
- Trap primers can automate this.
Toilet seals and vents
A failed toilet wax ring lets gas escape at the base. A blocked vent can siphon traps dry.
- Gurgling drains suggest vent issues.
Cracked pipes
Cracked cast iron or loose joints can release gas. A smoke test can locate them.
- Call a plumber if the source is not obvious.
A quick test you can do
Pour a litre of water into every floor drain and any shower or basin nobody uses, wait a day, and see whether the odour fades.
- If it does, a dry trap was the cause.
- If it lingers near one toilet, rock the bowl gently; any movement suggests the seal underneath has failed.
Outside smells
A sewer smell outside near the house may come from a roof vent, a cracked lateral or a city sewer issue. Report city sewer issues to 311.
- Roof vents should release gas above the roofline.
Health and safety
Sewer gas is unpleasant and can be harmful in high concentrations. Ventilate and find the source.
Water heater smells
A sulphur odour that only comes with the hot side may come from the water heater anode, not the drains.
Clues to the source
- Smell near floor drain
- Smell at toilet base
- Gurgling drains
- Smell in a rarely used bathroom
- Smell after rain