From the Archive: Something in the Air
Getting Rid of Smelly Drains
A whiff of rotten eggs from the basement or a sour smell from the kitchen sink. Most drain odours have simple causes.
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Short answer
Most bad smells come from a dry trap, a dirty drain, or a venting problem. Start with the easy ones.
What you notice, what we usually find
| Symptom | Likely cause |
|---|---|
| Sewer smell from a floor drain | Dry trap that needs water |
| Smell only near one sink | Slime in the trap or a missing vent |
| Smell after rain | Cracked cleanout cap or venting fault |
Tracking it down
- Dry trap. Every drain has a U-bend trap; the water sitting in it is the seal against sewer gas. Rarely used floor drains, guest showers and basement sinks dry out. Pour in a litre of water, then a spoonful of cooking oil to slow evaporation.
- Gunk in the line. Kitchen sinks and bathroom basins collect grease, hair and soap that rot. Clean the stopper and trap, then flush with hot water.
- Overflow openings. Bathroom sink overflows collect grime. Clean them with a small brush.
- Disposal. Run it with cold water and a handful of ice, then flush.
- Washing machine. Run a cleaning cycle and check the standpipe.
- Toilet seal. A smell about the base can mean a broken wax ring.
If you smell gas rather than sewer, leave the home and call Enbridge Gas from outside. Natural gas has an added odour similar to rotten eggs.
What does not help
- Air fresheners hide the problem without fixing it.
- Pouring harsh chemicals into a smelly drain can damage pipes and seals.
- Covering a floor drain under flooring removes its ability to stay filled.
Stop and phone a plumber when
- 1A ceiling or wall starts dripping
- 2More than one drain backs up at once
- 3You smell gas or sewage indoors
- 4A valve will not turn or drips when touched
When to call
If the smell persists after these checks, the vent stack may be blocked, a drain pipe may be cracked, or the lateral may be backing up. Book a visit and mention which rooms smell and when. See drain cleaning and camera inspection.
Straight answers to common calls
Why does my basement smell like sewer only sometimes?
A floor drain trap that dries out between uses is a common reason.
Can a blocked roof vent cause smells?
Yes. Vents let sewer gas escape above the roof; a blockage can push it into the house.
Keep reading
- Drain Cleaning in Oakville
Slow sinks, gurgling tubs, a floor drain that backs up after a big wash day.
- Bathroom Drain Cleaning in Oakville
The tub takes ten minutes to empty.
- Things That Should Never Go Down a Drain
A toilet line is meant to carry three things only: water, human waste, and toilet paper.
- Sewer Camera Inspection in Oakville
Guessing at a buried pipe wastes money; the camera ends the guessing.
Ready when you are
One call books the visit. Tell us what you are seeing and we will tell you straight what it likely is.