Washing Machine Waste Pipe Smells? (here’s why & what to do)

If your laundry or kitchen fills with a foul smell every time you use your washing machine, you’ve found the right article. This is a relatively common problem that could have several different causes.

In this article I take a close look at the reasons why your washing machine is producing a bad smell and offer solutions to those issues.

What Causes The Washing Machine Waste Pipe To Smell?

There are several possible causes that could make the washing machine waste pipe smell which include;

Probable Cause	Solution
Washer’s Drain Hose Pushed Too Far Into Standpipe	Remove drain hose and reposition it
Detergent Build Up	Ensure that you only use the correct amount of detergent
A Build Up Of Dirt, Grime & Grease	Clean the drain pipe
Mould & Mildew Growth	Run a hot service wash and ensure the washer is aired after use
Insufficient Air Circulation	Open a window or install a fan in the room
Rodent Or Insect Infestation	Ensure the room is clean and tidy and contact a professional
Drain Clogged	Unclog the drain

Let’s take a closer look at each of these issues;

Washer’s Drain Hose Pushed Too Far Into Standpipe

The drain hose on your washing machine should be connected to a standing pipe with a U-bend at the bottom. The drain hose is simply pushed into this standing pipe and it’s essential that it’s not pushed in too far.

The drain hose should never be pushed into the standpipe any deeper than 6 inches (15 cm). Any deeper and it’s possible to create a vacuum which can cause all sorts of problems. 

One of which is that the U-bend which is designed to prevent any smells from the drain entering the room, fails to work properly. Unfortunately, the drain hose can move further into the standpipe due to the vibrational force created by the washing machine when in operation.

You should get into the habit of checking the drain hose’s position in the standpipe at least every 4 weeks to prevent this from becoming a problem.

Detergent Build Up

If you consistently use too much detergent and/or fabric softener, it can build up in the drain hose. This creates the perfect environment for germs and bacteria to grow which could be the cause of that foul smell.

The best way to prevent this from happening is firstly to only ever use the correct amount of detergent and fabric softener for the wash load you are running (consult the packaging for more details). 

You should also use the best type of detergent that you can afford. Inferior quality detergents can create many problems with the wash load and the washing machine as well as creating a blockage in the waste pipe.

Secondly you should run a hot service wash in the washing machine when it’s empty once a month to prevent the build up of detergent residue. You should use a commercial washing machine cleaner and follow the instructions on the package.

Or pour 1 cup of distilled white vinegar into the drum and run a hot (90^o C) service wash.

A Build Up Of Dirt, Grime & Grease

A build up of detergent and fabric softener can also collect grease and dirt from the laundry to create even more germs and bacteria. These bacteria create that foul smell and need to be removed.

To tackle the issue immediately, pour hot water down the standpipe before running a hot (90^o C) service wash. This should be repeated every month to prevent any more unpleasant smells from forming.

Mould & Mildew Growth

Mould and mildew spores are ever present in our water supply and in the air that we breathe. They thrive in dark, damp places which describes the drain hose and standpipe perfectly.

You should run a hot (90^o C) service wash once a month to help prevent the growth of mould and mildew and ensure the washroom is well ventilated to prevent it becoming too damp.

You could consider running a fan in the room, opening a window or installing a dehumidifier if the room is particularly humid.

Insufficient Air Circulation

I already touched on ventilation in the last point, but it’s important enough to get its own heading. If there isn’t enough air circulating around the room, bad smells stay for longer.

Consider opening a window or installing a fan to ensure adequate airflow. An extractor fan might be the way forward as it will expel all of the moist air from the room. 

Rodent Or Insect Infestation

Unfortunately, rodents and insects are attracted to damp environments and the area around the drain hose of your washing machine could be the perfect spot for them to breed.

The smells that can be created by insects and rodents can be quite foul and also unhealthy. If you suspect that an infestation is the cause of your problem, you should contact a professional who will know how to deal with the problem and prevent it from happening again.

They might suggest installing pest-proof screens on the windows and doors as well as using bait traps.

Drain Clogged

Over time the drain that the waste pipe runs into could become clogged with dirt, grime, detergent residue, etc. Germs and bacteria then breed in this dark, damp environment and the smells they produce come up the pipe and into your home.

Running the washer disturbs the clog and makes it release even more of that pungent smell. The best way to solve this is to use a commercial drain cleaner to clean the drain and remove the smell.

If this is a step too far, you should contact a local plumber to investigate and sort it for you.

Ways To Give Your Washing Machine & Pipes A Good Clean

There are several ways to ensure your washing machine and waste pipes are cleaned properly these include;

White Vinegar & Bicarbonate Of Soda

Vinegar and bicarbonate of soda when combined create a powerful cleaning agent. All you need to do is;

1. Pour 1 cup of bicarbonate of soda down the waste pipe
2. Then pour 1 cup of white vinegar down the waste pipe
3. Allow 10 minutes to pass
4. Pour 1 gallon of hot water down the waste pipe to flush the pipe clean

The chemical reaction caused when you mix bicarbonate of soda and vinegar causes the solution to fizz and expand into a cleaning foam. This clears many germs, bacteria as well as dirt, grease, grime and other undesirable particles that are likely to be causing the foul smell.

Lemon Juice, Salt & Bicarbonate Of Soda

This solution works in much the same way as above, also using natural ingredients. All you need to do is;

1. Mix 1 tablespoon of salt with 1 tablespoon of white vinegar and the juice of 1 lemon
2. Pour the solution down the waste pipe
3. Allow 10 minutes to pass
4. Pour 1 gallon of hot water down the waste pipe

Hot Water & Washing Up Liquid

Washing up liquid is a great way to remove grease and oil from the waste pipe. All you need to do is;

1. Pour 1 cup of washing up liquid down the waste pipe
2. Allow 10 minutes to pass
3. Pour 1 gallon of hot water down the waste pipe

The washing up liquid will work on the grease and grime and the hot water will wash it all away.

Bleach

If you want to use a more powerful drain cleaner, try this method. All you need to do is;

1. Mix 1 cup of bleach into 1 gallon of hot water
2. Pour the solution down the waste pipe
3. Allow 10 minutes to pass
4. Pour 1 gallon of hot water down the waste pipe

It is essential that you don’t omit step 4 because bleach can damage pipework if left too long. This is also why the bleach should be watered down before use.

SEE ALSO: Do You Need To Elevate A Washing Machine Drain Hose?

Frequently Asked Questions