Mold is common in washing machines, but it generally has a musky odor. When the washing machine smells like rotten eggs, that's usually caused by hydrogen sulfide gas. Hydrogen sulfide is a primary component of sewer gas, and it's a byproduct of bacteria metabolism.
Bacteria usually inhabit sewers, but they can also live quite happily in the washing machine. If you're wondering what they would find to eat there, the answer is probably laundry detergent. When you don't clean your washing machine often enough, detergent collects on rubber parts, and those parts become breeding grounds for stinky bacteria that give your washing machine a sulfur smell.
The Smell Could Be Coming From the Sewer
It's usually easy to distinguish a problem with the drain from a problem with the washing machine itself. When you pull the washing machine away from the wall, you'll notice that the drain hose is hooked onto the drain standpipe and isn't permanently connected. Remove the washing machine hose and take a whiff of the drain pipe, and you'll get your answer.
If the drain is stinky, you could have a venting problem that is causing water to be sucked out of the P-trap. If so, you'll probably notice similar odors in other drains in the house. If you suspect venting or other drain problems, now is the time to call a plumber and get them fixed.
It's also possible that the standpipe itself is providing a home for odor-causing bacteria. You can clean it by pouring a half cup of baking soda into the standpipe and following this with a half cup of vinegar. The mixture creates a disinfecting foam that kills the bacteria.
Why the Washing Machine Smells Like Sewage
If the odor doesn't seem to be coming from the drain, you've got bacteria in the washing machine. One of the main reasons this happens is if you habitually wash clothes at low temperatures. Ideally, the wash water should be 140 degrees Fahrenheit.
You could also be using the wrong kind of detergent or the wrong amount. Front-loading washing machines are particularly vulnerable to soap scum build-up, so if your front-loading washer smells like sewage, switch to high-efficiency detergent. Look for the letters "HE" on the detergent container and follow the instructions for using it.
A third cause of bacteria growth is that you leave the door or lid closed when you aren't using the washer. Bacteria thrive in moist environments, and they make your washing machine stink. They'll die if you leave the door ajar and allow everything to dry out.
How to Get Rid of the Washing Machine Sulfur Smell
If you get rid of the odor-causing bacteria in your washer, you'll get rid of the smell. You can then use proper washing techniques to keep the bacteria and the smell from returning. Here's how to clean the washer:
- Physically clean soap build-up off the rubber gasket around the door or lid using a rag. Improve cleaning efficiency by using a bathroom cleaner that contains bleach or by dipping the rag in a 1:10 solution of bleach and water or a 1:1 solution of vinegar and water.
- Fill the bleach dispenser with liquid bleach and run the empty washing machine through a cleaning cycle. If you're sensitive to bleach, use baking soda and vinegar instead. Start the cleaning cycle and pour in 1/2 cup of baking soda and 2 cups of distilled white vinegar when the tub is half full.
- Leave the door or lid open overnight after the cleaning cycle is complete. Make sure the interior has completely dried out before you do your next wash.
Chris Deziel is a contractor, builder and general fix-it pro who has been active in the construction trades for 40 years. He has degrees in science and humanities and years of teaching experience. An avid craftsman and musician, Deziel began writing on home improvement topics in 2010. He worked as an expert consultant with eHow Now and Pro Referral -- a Home Depot site. A DIYer by nature, Deziel regularly shares tips and tricks for a better home and garden at Hunker.com.