Mold in Dishwasher

Ever opened your dishwasher and spotted black or pink spots around the door seal, or noticed a musty smell even after a wash cycle? You may have mold growth in your dishwasher. It’s one of the most common places for mold in a kitchen, and in most cases you can clean it out yourself.

A dishwasher gives mold everything it needs: warm water, steam, darkness and a steady supply of food scraps. When the door stays shut between loads, the inside never fully dries, and mold settles into the places where water and food collect.

Below we cover what causes mold in your dishwasher, where it hides, how to tell mold from stains, how to clean it out step by step, and when the real problem is a leak behind the machine.

Quick answer: how do you get rid of mold in a dishwasher?

Take out the racks and the filter and scrub them in hot, soapy water, then scrub the rubber door seal, the door edges and the spray arms. Run a hot empty cycle with a cup of white vinegar on the top rack, then a second short cycle with baking soda on the bottom. Leave the door open to dry, and clean the filter about once a month. If a musty smell or spots come back within a few weeks, or you see mold on the cabinet or floor next to the machine, a hidden leak is the likely cause.

Worried About Mold in Your Dishwasher? Get a Free Inspection!

Cleaned the dishwasher and the smell or spots keep coming back? Contact Mold Busters for a free virtual mold inspection. Our experts will help you work out whether the problem is the machine or a leak behind it, and recommend a plan to tackle it.

What causes mold growth in your dishwasher?

Food scraps collect in the filter at the bottom of the tub, in the folds of the rubber door seal, along the bottom edge of the door and in the spray arms. Add water, heat and a door that stays closed, and mold grows there quickly. The door seal is the favourite spot: you can’t see into its folds, so growth goes unnoticed until you notice a smell or black spots.

It is also very common. Researchers who swabbed 189 home dishwashers in towns and cities around the world found fungi in 62% of them, mostly on the rubber seal in the door, and more than half of those machines (56%) carried black yeasts, fungi that put up with the heat, salt and strong detergents inside a dishwasher (Zalar and colleagues, Fungal Biology, 2011). Black spots on a dishwasher seal are normal wear, not a sign that something is badly wrong, but they come back unless the seal and filter are cleaned regularly.

A dishwasher can also cause mold outside the machine. A slow leak from the water supply line, the drain hose or the door can soak the cabinet sides, the subfloor and the wall behind it for months before anyone notices, and cleaning the inside won’t fix that. If you notice staining, swelling or a musty smell in the cabinets next to the dishwasher, contact a professional inspector at Mold Busters to find the source.

Signs of mold inside your dishwasher

Some signs are obvious, like black spots on the door seal. Others are hidden inside the machine or behind it. Here are the places to check first.

Dishwasher smell

A musty or foul smell when you open the door is usually the first sign. The most common source is the filter at the bottom of the tub: Bosch explains that with every cycle, food particles and debris get stuck in it. Standing water is the next suspect. Whirlpool notes that water left at the bottom “due to drainage issues or a blocked filter can cause unpleasant smells.” If cleaning the filter and the seal does not clear the smell, mold may be growing somewhere you can’t see, including behind the machine.

Mold on dishes and dishwasher rack

Mold on dishes usually means one of two things. Dirty dishes sat in a closed dishwasher for several days before it was run, giving mold time to grow on the leftover food. Or clean dishes were put away damp, or left in a closed machine that never dried. Racks collect food the same way, especially where the coating is chipped.

What to do with the dishes: hard items such as glass, ceramic and metal can be scrubbed and washed again once the machine is clean. Wooden spoons, cutting boards and scratched or cracked plastic with mold growing into them are hard to clean fully and are best thrown away. If food itself has gone moldy, see our guide to mold on food.

If you need professional help, consider our virtual inspection service.

Mold in drain hose

The drain hose carries food scraps and dirty water out of the machine, and a film can build up inside it, especially where it sags or loops. A kinked or blocked hose, or a clogged filter, leaves dirty water standing in the bottom of the tub, which smells and feeds growth. If water sits in the tub after a cycle, clean the filter first. If it still doesn’t drain, have an appliance technician check the hose, because a blocked drain can also leak under the machine.

Mold in vent

Some dishwashers have a vent near the top of the door that lets steam out while the dishes dry. The steam leaves moisture around the vent and along the door edge, so check and wipe this area when you clean the seal.

Mold behind dishwasher

If you have the telltale musty smell but the inside of the dishwasher is clean, the mold may be growing outside it. A slow leak from the water supply line, the drain hose connection or a worn door seal can soak the wall, the cabinet sides or the floor under the machine. Particleboard cabinets, drywall and wood subfloors soak up water and stay damp, which makes them easy places for mold to grow, and you often can’t see it until the dishwasher is pulled out.

Before pulling a dishwasher out, turn off its power at the breaker and close the water supply valve, usually under the sink. Look for staining, swelling or soft spots on the cabinet sides and floor, drips at the hose connections, and a musty smell that gets stronger as the machine comes out. A small patch on a hard surface can often be cleaned, but mold that has soaked into the subfloor, drywall or cabinet base usually has to be cut out, after the leak is fixed. Our guide to preventing mold in the kitchen covers leak checks around sinks and appliances. If you find more than a small patch, contact Mold Busters for an inspection. Our teams in Montreal and Ottawa are ready to assist you.

What does mold in your dishwasher look like?

Mold in a dishwasher most often shows up as black or grey spots, slime or fuzz in the folds of the rubber door seal, along the bottom edge of the door, around the filter and drain, and in the spray arm holes. Pink, orange or rust-coloured film is also common, but it is often not mold at all. The check below covers the most common look-alikes.

Mold growing outside or behind your dishwasher can look like black, green or dark brown spots on the cabinet sides, the wall or the underside of the countertop, or a large patch on the subfloor that has been growing unnoticed for a long time. Growth like that comes from a leak, and once the leak is fixed it usually needs professional remediation.

Orange or pink? Check this first

Orange or pink stains on plastic parts and the tub are often from tomato-based food. KitchenAid notes that washing large amounts of dishes with tomato-based soil “can cause a pink/orange appearance,” that the stains fade over time, and that they do not affect how the dishwasher works. Scraping off tomato sauce before loading helps.
Brown or rust-coloured stains that keep coming back are likely from a high iron content in your water, especially on a well. A dishwasher cleaner made for mineral and iron deposits removes them. If you need it more than once a month, KitchenAid recommends installing an iron removal unit.
Pink or orange slime in the seal, the filter or the corners is usually a bacterium called Serratia marcescens, not a mold. It’s often called pink mold, and the cleaning steps below remove it.
Black, grey or green spots, fuzz or slime that grow back after you wipe them are most likely mold or black yeast. Follow the cleaning steps below.

What types of molds can grow in your dishwasher?

Several kinds of mold, yeast and bacteria grow in dishwashers. You can’t tell them apart by eye, but they are all cleaned out the same way.

Here are the ones you’re most likely to see. If you find growth outside the machine, or it keeps coming back after a thorough clean, contact Mold Busters for an inspection to find out what is growing and why.

Black mold in dishwasher: dark spots or slime in the door seal, around the drain and along the bottom edge of the door. Studies of dishwashers have found black yeasts more often than any other fungus. Read more about black mold.
Orange mold in dishwasher: true orange mold is possible, but orange film in a dishwasher is more often tomato staining, iron in the water or bacteria. Use the check above before assuming it’s mold.
Pink mold: pink or salmon-coloured slime in the seal and corners. Despite the name, it’s usually a bacterium, Serratia marcescens, that feeds on soap film and food residue in damp places.

Is mold inside your dishwasher dangerous?

Mold in a dishwasher is a cleaning problem rather than an emergency, but it’s not something to leave. You can’t tell which type of mold it is by looking, so clean it out properly rather than just running another load. CMHC advises that you can clean a small mould problem yourself if you are in good health, so if someone in your home has health concerns, have someone else do the cleaning. And as Health Canada puts it, “If you think that your health problems might be related to mould, talk to your health care professional as soon as possible.”

How do you prevent mold inside your dishwasher?

The best way to prevent mold in your dishwasher is to keep food scraps out of it and let it dry:

Scrape plates before loading. You don’t need to rinse everything, but large scraps end up in the filter.
Clean the filter about once a month, or more often if you run the machine every day.
Wipe the door seal and the bottom edge of the door every week or two with a cloth and warm, soapy water, then dry it.
Leave the door open a crack after each cycle so steam can escape and the inside can dry. Keep it out of reach of small children and pets.
Don’t leave dirty dishes in a closed machine for days. Run it, or use a rinse-only cycle if your model has one.
Run a hot, empty cleaning cycle every month or two with white vinegar or a dishwasher cleaner your manual allows.
Watch for leaks: water on the floor, a swollen kickplate, or a musty cabinet next to the machine.

How do you remove mold inside your dishwasher?

A small amount of mold inside a dishwasher can almost always be cleaned out by hand. Health Canada says you can generally clean small areas of mould yourself with water and dish detergent, and that there’s no need to use bleach. Wear rubber gloves, and open a window or turn on the range fan.

Turn it off. Switch the dishwasher off, and turn off its breaker if you’ll be reaching into the bottom of the tub or the spray arms.
Take out the racks and utensil basket and wash them in the sink with hot, soapy water.
Clean the filter. Twist out the filter at the bottom of the tub (your manual shows how for your model) and scrub the mesh and every piece with an old toothbrush and hot, soapy water. Wipe out the filter housing too.
Scrub the door seal. Pull back the folds of the rubber seal and scrub them with a toothbrush and warm, soapy water, or a cloth dampened with white vinegar. Then do the bottom edge of the door, the hinges and the corners of the tub.
Clear the spray arms. Poke debris out of the spray holes with a toothpick, and rinse the arms if they come off.
Run a vinegar cycle. Put everything back, stand a dishwasher-safe cup of white vinegar upright on the top rack, and run the hottest cycle with no dishes and no detergent.
Run a baking soda cycle. Sprinkle about a cup of baking soda on the bottom of the empty tub and run a short hot cycle. Keep it a separate cycle: mixed together, vinegar and baking soda mostly cancel each other out.
Dry it out. Leave the door open for a few hours so the seal and tub dry completely.

About bleach: you don’t need it, and never mix it with vinegar, ammonia or other cleaners. Samsung warns not to use bleach in a dishwasher with a stainless steel interior, “as it may damage or discolor the interior.” Check your manual before using bleach or any commercial cleaner.

When to call a professional: if growth or a musty smell comes back within a few weeks of a thorough clean, if water keeps standing in the tub, or if you find mold on the cabinet, wall or floor around the dishwasher, the cause is likely a leak or hidden growth. Contact Mold Busters to inspect and, if needed, remediate the area around your dishwasher.

A moldy dishwasher is common and usually easy to fix: clean the filter and the door seal, run a hot vinegar cycle and let the machine dry with the door open. If the smell or growth keeps coming back, look beyond the machine for a leak. The same habits keep mold out of a front-load washer too: see our guide to mold in a washing machine.

Frequently Asked Questions

How do I get a moldy or musty smell out of my dishwasher?

Start with the filter, which is where most smells come from: twist it out and scrub it in hot, soapy water. Then scrub the folds of the door seal, clear the spray arm holes and run a hot empty cycle with a cup of white vinegar on the top rack, followed by a short cycle with baking soda. If the smell comes back within a few weeks, check for water standing in the tub (a drain problem) or a leak and hidden mold behind the machine, and contact Mold Busters if you find growth outside the dishwasher.

Can mold inside a dishwasher make you sick?

We can’t give medical advice, and how mold affects people varies from person to person. What we can say is that mold in a dishwasher is common and can almost always be cleaned out, so there’s no reason to live with it. If someone in your home has health concerns, have someone else do the cleaning. Health Canada’s advice is: “If you think that your health problems might be related to mould, talk to your health care professional as soon as possible.”

Can a dishwasher clean mold off my dishes?

Yes, for hard items. Glass, ceramic and metal dishes that came out of a moldy dishwasher can be washed again once the machine is clean; scrub any spotted pieces first. Wooden, cracked or scratched plastic items with mold growing into them are hard to clean fully and are best thrown away. Then deal with why the mold was there: dishes left for days in a closed machine, dishes put away damp, or growth in the seal and filter.

Can I run my dishwasher if it has mold in it?

It’s better to clean it first. Running loads through a moldy filter and seal leaves residue on your dishes and gives the mold more food. Clean the filter, the seal and the spray arms, run a hot vinegar cycle, and then use it as normal.

Can I use bleach to clean mold in my dishwasher?

You usually don’t need to. Health Canada says there’s no need to use bleach to clean small areas of mould, and soap and water or white vinegar does the job inside a dishwasher. Some manufacturers, including Samsung, warn against bleach in stainless steel tubs because it can damage or discolour the interior. If your manual does allow bleach, never mix it with vinegar, ammonia or other cleaners.

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