A sewage smell from your washing machine is alarming — and it shouldn’t be ignored. The good news is it’s usually a drain-related issue, not a sign that your machine is fundamentally broken. Our Winnipeg repair team can diagnose and fix the source of the smell.
Where Does Sewage Smell Come From?
Unlike mildew or musty smells that come from inside the machine, sewage-like odors almost always originate from the drain system. The smell is typically sewer gas — a mix of hydrogen sulfide, ammonia, and methane — that’s escaping into your laundry room.
The Plumbing Anatomy
Your washing machine drains into a standpipe (a vertical pipe usually 2-3 inches in diameter). The standpipe connects to your home’s drain system through a P-trap — a curved pipe section that holds water to block sewer gas from entering your home.
If this P-trap dries out or is missing, sewer gas travels freely from the sewer line into your laundry room — often seeming to come from the washer itself.
Common Causes of Sewage Smell from Washers
1. Dry P-Trap in Drain Standpipe
Most common cause. If the washing machine isn’t used regularly:
- The water in the P-trap evaporates
- Sewer gas has a clear path into the room
- The smell seems to come from the drain or washer area
Solution: Pour 500ml of water into the drain standpipe. The smell should disappear within minutes as the trap refills. Consider periodic “flush” cycles if you travel or rarely use the machine.
2. Drain Hose Installed Incorrectly
If the drain hose is inserted too deeply into the standpipe or is sealed around the standpipe entrance, it can create a siphon effect that empties the P-trap after each wash cycle.
Solution: Ensure the drain hose is loosely inserted (not sealed) and doesn’t reach the bottom of the pipe.
3. Drain Hose Sitting in Standing Water
If the drain hose end is submerged in standing water in a utility sink or floor drain, water can siphon back and cause odors.
Solution: Elevate the drain hose end so it’s above any water level in the drain area.
4. Clogged or Dirty Drain Hose
Biofilm, soap scum, and lint can accumulate inside the drain hose, decomposing and producing gas.
Solution: Disconnect and clean the drain hose with warm water and vinegar or a drain cleaner.
5. Clogged Pump Filter
A heavily clogged pump filter traps decomposing debris that produces foul odors.
Solution: Clean the pump filter monthly. Location varies — usually behind a small panel at the front bottom.
6. Missing Drain Trap
In some homes, particularly older Winnipeg properties, the drain standpipe may not have been installed with a P-trap.
Solution: A plumber needs to install a proper P-trap in the drain line.
7. Venting Issues in Plumbing
Improper drain venting can cause sewer gas to push past traps throughout the system.
Solution: A plumber should inspect the drain venting for your laundry area.
Sewage Smell vs. Mildew Smell — How to Tell
Sewage Smell
- Sharp, sulfur-like (rotten egg) or waste-like odor
- Present even when machine is off
- Comes from drain area direction
- Worse after machine runs
Mildew/Musty Smell
- Musty, damp, earthy odor
- Comes from inside the drum
- Often noticed in washed clothes
- Caused by mold in drum or seal
If you’re getting a mildew or musty smell rather than sewage, see our article on how to stop your washing machine smelling.
Winnipeg-Specific Drain Considerations
Older Homes
Many Winnipeg homes — especially in established inner-city neighbourhoods — have older plumbing that may:
- Have missing or deteriorated P-traps
- Use older drain sizes that don’t properly seal around modern drain hoses
- Have venting that wasn’t designed for modern high-volume washing machines
Basement Laundry Rooms
Basement drains in Winnipeg homes can be more susceptible to:
- Floor drain traps drying out in hot summers
- Drain backup during heavy rain events
- Older cast iron pipes with rougher surfaces that accumulate biofilm
Cold Winters
During Winnipeg winters, less-used laundry machines (like cottage or secondary properties) can have P-traps that freeze or evaporate in heated spaces, creating sewer gas issues.
Step-by-Step Sewage Smell Diagnosis
- Sniff around the drain area — if strongest at the standpipe, it’s likely a drain trap issue
- Pour water into the standpipe — wait 10 minutes and see if smell resolves
- Check drain hose position — ensure it’s not sealed or submerged
- Clean the pump filter — check for foul-smelling decomposing debris
- Run an empty hot wash — to flush drain hose
- If smell persists — call our team to inspect the drain connection and washer drain system
When to Call a Plumber vs. Appliance Repair
Call Us (Appliance Repair) If:
- Pump filter is clogged
- Drain hose is damaged or incorrectly installed
- Washer drain system needs cleaning
- The smell started when the washer was installed
Call a Plumber If:
- The standpipe has no P-trap
- Drain venting appears inadequate
- Multiple drains in the home smell (not just the washer area)
- Adding water to the standpipe doesn’t resolve it
Get Your Washer Drain Smell Fixed in Winnipeg
Our Winnipeg repair technicians diagnose washing machine drain odors and fix the appliance-side causes. We’ll also advise you if the issue is in your home’s plumbing so you know exactly who to call.
Contact us today to investigate and fix your sewage-smelling washing machine in Winnipeg.