You run a hot cycle, add detergent, and pull out towels that smell like a damp basement. If that sounds familiar, there may be mold in your washing machine, or at least some other microbial buildup, quietly growing in the warm, wet spots you never see.
It’s not as rare as it sounds. In a 2015 study of 70 household washing machines in Slovenia, 79% tested positive for fungi, with samples taken from detergent drawers and rubber door seals. A 2021 review in Applied and Environmental Microbiology cites the study. That doesn’t mean 79% of washers have visible mold, but it shows how readily fungi settle into the damp parts of a machine.
Here’s how to tell what you’re dealing with, how to clean it without damaging your machine or your lungs, and how to keep it from coming back.
How to tell if your washer has mold
Check the door seal. On a front-loader, pull back the rubber gasket and look in the folds for black, green or brown spots and a slimy film. Water and lint collect there after every load.
Look at the detergent drawer. Slide it out if it comes free and check the cavity behind it too. Dark spots and gunk in there are common.
Look under the lid. On a top-loader, check the underside of the lid, the rim of the tub and any dispensers.
Use your nose, but don’t stop there. A musty or sour smell coming from the machine, or from clothes that just came out of it, is the classic warning sign.
A smell isn’t proof of mold. Bacteria and fungi both produce laundry odors, according to the same review, and soap and detergent residue can build up in the same spots. Look before you assume. For smells that linger elsewhere in the house, here’s how to remove odors from your home.
The same 2015 study found that machines with fungi were most often run at 40°C (104°F), while fungus-free machines were most often run at 60°C (140°F). Detergent and softener residue and wash temperature were the most important factors the researchers identified. That’s an association, not proof that a hot wash prevents mold, but it’s one reason a regular hot cleaning cycle is worth it.
Before you clean: check what your manual says about bleach
Here’s what most cleaning guides skip. Appliance brands don’t agree on bleach.
Whirlpool: for stubborn mold or mildew on the gasket, its guide calls for 3/4 cup of liquid chlorine bleach in 1 gallon of warm water, left on for about 5 minutes before scrubbing.
LG: its support page says to avoid chlorine-based or acidic washer cleaners because they may cause discoloration or corrosion, and recommends an oxygen-based washing machine cleaner instead.
Look up your model in the manual or on the manufacturer’s support site before you pick a product. If you can’t find guidance, start with the manufacturer’s recommended cleaner or cleaning cycle, if one is specified for your model.
Never mix bleach with other cleaners. The Washington State Department of Health says bleach plus ammonia makes toxic chloramines, and bleach pl
