It is easy to forget to clean the things we use to clean. The washing machine, vacuum cleaner, and dishwasher are household appliances we rely on to keep our homes clean, but they are often overlooked in routine maintenance. Often, those appliances let you know they need cleaning by developing a foul odor you can't ignore.

In a washing machine, that odor is almost always moldy, and it is a sign that mold and mildew have developed in the machine’s rubber parts, including gaskets and hoses, as well as in its dispensers, filters, and traps. This guide explains why mold growth occurs, how to prevent it, and what to do if your washer develops a mold problem.

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What Causes Mold Growth in a Washing Machine and How to Prevent It

Washing machines are inviting, attractive homes for mold, as they provide numerous conditions in which mold thrives. They are dark and damp, and residue from laundry products, such as detergent, fabric softener, and scent beads, as well as soils and bacteria found on our clothes, can linger in the washer, providing food for mold. 

Trapped moisture is the biggest contributor to mold growth in a washer, particularly in the rubber gasket, detergent dispensers, and the machine’s filter(s). To prevent moisture from getting trapped, avoid leaving the washer door closed between loads, or wipe the door dry after use. Additionally, routine cleaning and maintenance, along with avoiding overuse of laundry products that can lead to residue buildup in the machine, can help prevent mold growth in the washer. 

If your laundry room or area is prone to high humidity or has poor ventilation, you may notice mold growing more quickly. Adding a fan, dehumidifier, a chemical desiccant like DampRid, or a moisture-absorbing plant to your laundry room can improve humidity levels and increase air circulation. 

What to Use to Clean a Moldy Washer

When a washing machine has developed mold, a deep cleaning is typically required. While washing machine cleaning tablets are a good choice for routine maintenance, mold remediation may require a more targeted product.

Many washing machine manufacturers recommend using chlorine bleach to eliminate mold and mildew. However, hydrogen peroxide is another good choice, as is distilled white vinegar, which is safe to use in a washing machine in moderation (excessive use can damage rubber seals, gaskets, and hoses). Regardless of which mold eliminator you choose, it is important to use these products safely.

Never mix chlorine bleach with vinegar or hydrogen peroxide, as the combination produces a toxic gas that can sicken or kill humans and animals.

Quick Tips for Cleaning a Moldy Washing Machine

If you catch a whiff of mold when loading or unloading the washer, the problem may be minor and can be fixed quickly. The rubber gasket, which seals around the door, traps dirt, product residue, and moisture, making it a prime breeding ground for mold.

To clean the gasket, gently pull back the flexible rubber and wipe the interior and its folds with a microfiber cloth dipped in white vinegar. If there is significant mold, spray the gasket with vinegar, leave the door open, and allow one minute for the vinegar to penetrate and break down the buildup. Then, wipe it clean with a damp microfiber cloth.

While the gasket is drying, open the machine’s dispensers to check for mold or product buildup. If the dispensers are removable, wash them by hand in hot, soapy water. If they are not removable, wipe out any residue using a damp microfiber cloth. Then apply white vinegar to the dispensers to remove mold and eliminate odors.

If visible mold remains or the machine still smells moldy after trying these quick cleaning methods, deeper cleaning is necessary.

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How to Deep Clean a Moldy Washing Machine

Here’s how to deep clean a moldy washing machine:

1. Empty the Washer

Ensure the washer drum is empty. If there is detergent, fabric softener, or bleach in the machine’s dispensers, empty them. 

2. Add Cleaning Agent

When the machine is empty, add the cleaning agent you will be using to the machine, either directly into the drum or into the dispensers.

• Chlorine Bleach: Pour 1 cup of chlorine bleach directly into the drum, or put ½ cup of chlorine bleach in the detergent dispenser.
• Hydrogen Peroxide: Pour 1 cup of hydrogen peroxide directly into the drum, or add ½ cup to the detergent dispenser.
• White Vinegar: Pour 2 cups of white vinegar directly into the drum, or put 1 cup of white vinegar in the detergent dispenser.

3. Run a Hot Water Cycle

With the machine empty, run a normal cycle using hot water; opt for a large-load setting to ensure enough water flows through the machine to clean it thoroughly. If your machine has a sanitize setting, you can also use that.

4. Clean the Dispensers

Refer to the user’s manual (if you can't find a paper copy, search online to find your washing machine's manual) and follow the manufacturer’s instructions for cleaning the dispensers. The manual will also instruct you on how to remove the dispensers, if possible, for deeper cleaning.

If the dispensers are removable, soak them in hot water and dish soap for 10 minutes, and then wash them with a sponge, dishcloth, or soft-bristled scrub brush. Rinse and dry them well and return them to the machine. If the dispensers are not removable, use a damp microfiber cloth to wipe away any residue, then apply white vinegar to the dispensers to remove mold and eliminate odors.

5. Clean the Gasket and/or Center Agitator

Clean the rubber gasket with a microfiber cloth dipped in white vinegar. If there is significant mold, spray the gasket with vinegar, leave the door open, allow 1 minute for the vinegar to penetrate and break down the buildup, then wipe it clean with a damp microfiber cloth.

The center agitator in top-loading machines can be another area where mold buildup develops, especially if it also serves as a fabric softener dispenser. To clean it, remove the fabric softener tray, then soak this piece in hot water to dissolve any product buildup. Then, use a long-handled brush or a cloth and warm water to wipe the inside of the agitator clean. Return the tray to the agitator.

6. Clean the Lint Trap

Your washing machine has a filter that is similar to the lint trap in a dryer. It should be cleaned regularly to prevent mold from forming. To clean the filter, locate it (either in the center agitator, in the drum’s top lip, behind a trap door on the front of the machine, or near the water pump or drainage hose). Remove the filter, and wipe the area around the filter’s housing. Soak the filter in a bowl of hot soapy water for 10 minutes, then gently scrub it with a soft-bristled brush. Return the filter to its housing.

7. Run a Short Wash Cycle (Recommended)

Running a short cycle after performing a deep cleaning cycle and hand-detailing the dispensers, gaskets, and filters can help to flush out any lingering residue from the cleaning process. While a second short wash cycle in an empty washer is not essential, it is recommended as a final step in the overall deep-cleaning process.