Washing Machine Smells Like a Sewer? 4 Quick Fixes

A sewer smell from a washing machine is often caused by mold, mildew and bacteria trapped under the rubber door gasket/seal, water filter or P-trap. It could also be caused by a dry P-trap or clogged vent stack.

Bacteria, mold and mildew thrive in a damp and dark surfaces. Both of those conditions are present in a washing machine. Often these places also have a low oxygen concentration, another favorable condition for the organisms

If you notice that your washing machine only smells when draining, most likely you have a clogged vent stack or a partially clogged drainpipe. When this is the case you will notice that the washing machine also drains slowly.

To get rid of a sewage smell from a washing machine, clean under the washer’s door seal with a rag, clean the detergents dispenser, remove and clean the water filter and lastly clean the waist pipe. In case you suspect the vent stack is blocked, climb to the roof of the house and unclog it.

How to Get Rid of Sewage Smell from a Washing Machine

From experience, sewer smells in the laundry room do not come from the drum itself. It is always one of the hidden places. Most people clean their washing machines regularly but they often focus on the drum only.

Cleaning the drum only will not help you get rid of the smell. You have to attack the mold and bacteria where they are hiding, and you also need to do it regularly.

Let us look at the several ways you can use to get rid of the musty or sewer gas smell from your washing machine. I will start with a brief summary and then the detailed guide.

Run a Cleaning Cycle: Periodically run an empty washing machine cycle with hot water, detergent, and a cup of white vinegar or baking soda to clean the drum and eliminate odor-causing bacteria.
Clean the Seal: Check the rubber door seal for trapped dirt or debris, which can contribute to odors. Wipe it clean and leave the door ajar between washes to allow it to dry.
Empty the Drain Filter: Remove and clean the washing machine’s drain filter or lint trap regularly to prevent odor buildup.
Use HE Detergent: Use high-efficiency (HE) detergent and the recommended amount to avoid soap residue and mold growth.
Leave the Door Open: After each wash, leave the washing machine door and detergent dispenser drawer open to allow air circulation and prevent moisture buildup.
Clean the Dispenser Drawer: Regularly remove and clean the detergent and fabric softener dispenser drawer to prevent mold growth.
Inspect the Drain Hose: Check the drain hose for clogs or kinks that can trap water and lead to odors.
Check the Plumbing: Ensure there are no plumbing issues, like a sewer gas leak, causing the odor. Consult a plumber if needed.

And now the detailed guide:

1. Clean the Door Seal

In order to have a tight seal around the door (for front-load washing machines) a rubber gasket/seal is usually installed. The design of the seal allows water to collect under its flap and if not dried regularly it starts to stink.

Here is how clean a washing machine gasket/seal:

Pull up the seal flap and inspect the condition underneath it. I am sure you will find a lot of accumulated gunk.
Use a rag dipped in a cleaning solution and clean all around the seal. When it is all clean I like to use a separate dry rag to get rid of all the moisture from the seal.
Leave the washing machine door ajar in order for its interior to dry as well as allow free circulation of air. Remember mold thrive in areas with limited supply of oxygen.
If you have a top-load washing machine, scrub through the doors nooks and crannies (crevices) which are potential breeding grounds for mold and mildew.
Again, do not forget to leave the door ajar. In fact this is what you should do every time after using the washing machine.

2. Clean the Water Filter

Every washing machine comes with a water filter. Regardless of which model you are using you should have a filter at the bottom of the washing machine.

Brands like LG recommend that you clean the filter after every month while others like Samsung recommend once every 2 months is sufficient. Take time to check what your washing machine manufacturer requirements are and follow them.

The reason it is very important to clean the filter is that water that is left in the tub after every washing cycle drains there. If not cleaned out frequently, this water starts to stink horribly.

Before you start to clean the filter grab a small bucket or pan and a dry rag. Set the pan below the filter. The water inside the filter sometimes has such a foul moldy smell and you do not want to spill it on the floor.

Here is how to clean a washing machine’s filter:

Remove the cover. Just press the small tab at the top and the cover will pop out.
Drain the water in the hose. You will now see a hose (usually black) which is what you need to drain. Pull the hose out completely and remove the plug at the front. Start drain the water in the pan/bucket. It might take a while to drain completely. If any of the moldy water spills on the floor dry it off with a rag.

When all the water has drained pour it out somewhere else.
Remove the filter. To remove the filter, turn it counterclockwise and when loose pull it out. Drop it in a container with warm water and a cleaning solution.
Use an old toothbrush to scrub the filter thoroughly and dry it with a rag.
If the space you removed the filter is dirty as well, stick a wet rag in there and clean it as best as you can.
Screw the filter back in.
Put the plug on the hose and push it back inside.
Push the cover back in position.

Apart from the filter and door seal. you should as well clean the detergents dispenser. Wipe it clean with a wet rag and leave it open for some minutes (or even hours) to completely dry as well as get fresh air.

3. Clean the Washing Machine P-Trap and Waste Pipe

Every fixture in your house with a drain has a P-trap. If you don’t know how a P-trap looks like, look under your kitchen or bathroom sink and you will see a curved pipe which looks like a U or an inverted P.

A P-trap has 2 main functions in a drain:

It holds a little amount of water at all time. This water acts as a barrier, preventing sewer gases from coming up into the bathroom.
It traps potential clogs, preventing them from clogging the drainpipe further down the where it would be more difficult to unclog.

It is important for you to remember that all your fixtures drainpipes are interconnected and they all drain into the main house drainpipe which in turn drains into the city sewer lines.

If you have not used your washing machine for some time, the water inside the P-trap could evaporate and in the process break the barrier. When that happens, sewer gases will flow out through the washing machine drain opening and hence the sewage smell in the laundry room.

The Solution to this problem is the easiest. Just add a little amount of water in the washing machine and drain it. This water will replace the evaporated water and sewer gases will not flow through the drain gain.

A new washing machine that smells like a sewer is a sign that the P-trap was not properly installed. In this case the P-trap will have to be remove and reinstalled, usually by a licensed plumber.

How to Clean a Washing Machine P-Trap

If a dry P-trap is not the issue, you likely have gunk inside it as well as in the drainpipe/waste pipe where bacteria are breaking down the organic matter trapped there producing that horrible sewage odor.

The fact that you only do laundry probably once in a week, it gives ample time for mold and mildew to grown inside the trap. This is number one cause for a smelly front-load and top-load washing machines.

While cleaning the P-trap only is possible, it even better if you clean the tub/drum as well.

When it comes to killing mold, bleach is my number 1 choice for a cleaning agent. You should however use it on its won and not combine it with other cleaners.

Here is how to clean a Washing machine and P-trap:

Pour half a cup of bleach directly in the P-trap. At the back of the washing machine you will see where the draining tube is inserted in the . That is where you will pour the bleach. Let it sit there as you clean the tub.

Set your washing machine to the highest temperature.
Add 2 cups of bleach in a front-load washing machine but if you have a top-loader add 4 cups.
Start a wash cycle and let it run until the tub is full and the bleach is sufficiently mixed. Let the solution sit for 30 minutes.
Resume the cycle and let it run to completion.
Start a rinse cycle to completely flush out everything from the tub as well as P-trap.

In case for one reason or another you do not want to use bleach, use a vinegar and baking soda combination. Add 1 cup of baking soda and an equal amount of vinegar, although the amounts will vary depending on the size of your washing machine and start a cycle.

After running bleach through the tub and P-trap, I also like to follow it up with vinegar for that fresh smell as well as kill any remaining bacteria or mold.

Here is to clean your washing machine with vinegar:

Set your washing machine to the highest temperature.
Add 2 cups of white vinegar in a front-loader and 4 cups of the same in a top-load washing machine.
Start a wash cycle, let the tub fill and when the vinegar has properly mixed stop the cycle. Wait for 30 minutes.
Resume the cycle and let it run until it is complete.
Dry the door seal with a rag.
Leave the washer’s door ajar to allow air to freely circulate in and out.

And basically that is how to clean and deodorize a sewer smelling washing machine.

4. Clear the Vent

A vent stack is the vertical pipe that runs from the main house drainpipe and through the roof. It helps in expelling sewer gases from the drainpipe as well as allowing free flow air in the entire plumbing.

In order for your washing machine/bathtub/sinks to drain properly, there must be air in the drainpipe. If the vent is clogged, sewer gases will not have a way out and will be forced out through one of the drains in your house, the washing machine drain included.

If the above is the case, you will notice that:

You have a slow draining bathtub.
The toilet has a weak flush.
Bathtub gurgles after flushing the toilet.
Toilet bubbles after flushing or after draining the bathtub.
Sink gurgles when the washing machine drains.

Most of the time when you have a clogged vent, draining the tub or flushing the toilet creates a vacuum in the drainpipe forcing the water in the washing machine’s P-trap to be sucked out, and hence the gurgling sound. When that happens, sewer gases escape from your washing machine uncontrolled.

If you notice that your washing machine only smells when draining, you most likely have a clogged vent and in some cases a partial clog in the main house drainpipe. The water from the washing machine displaces the gases in the drainpipe forcing them out through the washer’s drain opening.

Here is how to unclog a vent stuck:

Climb to the roof of the house armed with a garden hose.
Check for clogs at the top of the vent and if any remove them with your hand.
Stick the garden hose inside the vent and use it to dislodge any clog there might be.
Have someone turn on the water to the hose and hopefully the weight of the water will be enough to dislodge the clog.
For tough vent clogs use a plumber’s snake.

If you suspect you have a partial clog or you just can’t seem to get rid of the sewage smell from your washing machine, I suggest you just call in a licensed plumber.

How to Prevent Sewage Smell in washing Machines

Clean the washing machine tub often with baking soda and vinegar.
Once every month clean the filter and drain water from the house.
Frequently clean the washing machine detergent dispenser.
Take your time to thoroughly clean the washing machine door seal.
Leave the door ajar after using and cleaning the washer.
Use the right detergent as well as the correct quantity.