A sewage odor points more toward the standpipe, trap, drain-hose insertion or stagnant plumbing than ordinary washer mildew. Sniff at the drum, the drain hose and the standpipe separately; a smell only at the standpipe is a plumbing source. Compare the hose insertion depth and the air gap with the installation manual.
What this covers
- Washing machines · odor
What it does not cover
Differential
Likely causes of “Washing machine smells like sewage”, and how to tell them apart
- 1
Gas from the drain is rising through a dry or missing trap
What separates it The smell is strongest at the standpipe or the wall box behind the washer and is worse after the machine has not been used.
How to confirm Sniff at the drum, the drain hose and the standpipe separately; a smell only at the standpipe is a plumbing source.
- 2
The drain hose is pushed too far into the standpipe with no air gap
What separates it The smell appears with slow draining and the hose is sealed tight, or a bubbling sound is heard from the drain.
How to confirm Compare the hose insertion depth and the air gap with the installation manual.
- 3
Stagnant water or biofilm in the tub or door gasket
What separates it A sour, mildew-like rather than a sewer smell, strongest when the door is opened after a cycle.
How to confirm Smell the gasket fold and detergent drawer; a sour smell here is machine residue rather than plumbing.
- 4
A nearby fixture is venting or backing up
What separates it The smell appears after a sink or toilet nearby is drained and gurgling can be heard.
How to confirm Run nearby fixtures one at a time and see whether the smell follows one of them.
Before you touch a setting
Record this first — changing settings destroys the evidence
- Where the smell is strongest: drum, drain hose or the wall standpipe.
- Whether it appears after nearby fixtures drain, and whether the washer drains slowly.
- How long the door stays shut after cycles.
Try in this order
0 of 4 completedObserve before changing anything
ReversibleDetermine whether the odor is strongest at the drum, drain hose or wall standpipe and whether it appears after nearby fixtures drain.
Isolate the failing boundary
ReversibleInspect the required air gap and hose depth and ask a plumber to confirm the trap and vent if the smell comes from the standpipe.
Apply the narrow correction
ReversibleClean the washer separately using its documented tub-clean process, but correct the plumbing source first.
Verify the result and stop at the boundary
ReversibleStop for sewer backup, leaking wastewater or unsafe gas accumulation.
Stop boundary
When this stops being a self-service repair
- !Stop for sewer backup, leaking wastewater or unsafe gas accumulation, and call a qualified plumber.
- !Correct the plumbing source first; cleaning the washer will not remove a smell that comes from the standpipe.
Evidence ledger
Sources behind this answer
Exact questions
Common questions
Is a sewer smell from a washer dangerous?+
Sewer gas can contain harmful gases in high concentration, so treat a strong or persistent smell as a plumbing problem and ventilate the area.
Why a sewage smell?+
A dry trap or standpipe.
How to fix?+
Check the hose height.
Could it be a drain?+
Yes.