There can be a many reasons for the musty smell in washing machines.
Common causes for the musty smell in washing machines
1. The main cause of the musty smell in washing machines that are top or front load because of overdoing it with detergent usage. It may create a residue on that mold can use as a food source. Mold thrives in the dark, moist environment a washer provides. To get rid of the musty smell in washing machines stop feeding the mold. Unless you are washing heavily soiled clothes you actually only need a tablespoon of detergent to get the job done. You need more when using hard water. If you are using municipal water or have a water softener, drop in a tablespoon and you are good to go. It works best with liquid detergents. When you use a efficiency washing machine use low sudsing detergents.
2. Fabric softener is the next culprit that causes the musty smell in washing machines. It is released in the rinse cycle so ends up as mold food stuck to the sides of the washer. Make the change to dryer balls or dryer sheets. Dryer sheets can cause their own problems so go easy. Cut them in half and consider using them more than once. They can cause some fabrics to be less absorbent and hang on to odors.3. Washing machine odor can result from not using the machine. If you expect to leave it unused for a length of time run it using a washing machine cleaner. You should also shut off supply hoses as a safety precaution against flooding on account of a hose breaking. Not that when bleach gets spilled on the rubber water supply hose it can weaken and rupture causing the laundry area to flood.4. If you like to wash with cold water you need to conduct some preventive maintenance in order to dissolve residue. Do a hot water washing or soaking cycle as the last cycle you use when washing several loads. This will prevent the residue from attracting mold and making that musty smell in washing machines.
5. Check to see if your water supply hose is firmly connected. Even the smallest of drips can build moisture under your washer and lead to mildew.
6. Ensure the drain pumps are free flowing without obstructions. Most front-loading machines have a filter “trap” that may need to be cleared.
7. There could also be black mold forming on the rubber along the front door of your washing machine. These should be removed by a cleaner or using a suitable tooth brush. See our section on mold removal for additional help.