Dry traps
An idle floor drain or fixture slowly loses the water plug in its trap. Pour water in.
Other causes
- Loose cleanout caps
- Failed toilet wax seal
- Vent blockage
- Cracked drain pipe
- Sump pit without a lid
Testing
Refill traps, tighten caps, wait a day. If the smell persists, call.
Sewer gas can contain hydrogen sulphide. Ventilate if strong.
Help
See floor drain clearing and camera inspection.
Unused fixtures
Basement showers, laundry tubs and guest bathrooms that are rarely used lose their trap water through evaporation. Run water in each fixture monthly. For floor drains, a trap seal device or a spoonful of mineral oil floated on the trap water keeps it from drying.
Vent problems
If the roof vent is blocked by ice, a bird nest or debris, drains may gurgle and traps can siphon dry, letting gas in. A failed air admittance valve under a sink can also release odour.
Cracked pipes
Persistent odour despite full traps may mean a cracked drain pipe, often under the slab or inside a wall. A smoke test or camera inspection can locate it.
When to put the tools down
Some of this is homeowner work and some is not. Stop and phone us if you see any of these:
- All the fixtures go sluggish together
- Water comes up the floor drain when you do laundry
- Toilet bubbles while a sink drains
- Soggy dip in the grass above where the lateral runs
- Anything involving the gas line, the venting or cutting into a wall
Quick answers
Could the smell come from the sump pit?
An open sump pit can release earthy or musty odours. A sealed lid helps, and sewage smells point elsewhere.
Can sewer gas hurt us?
Strong concentrations are a hazard. Open windows, air the space out and phone us.
Can a dry trap cause the whole smell?
Very often, yes. Refilling it is the first test before anything else.