Asking yourself, 'why does my dishwasher smell bad?' Don't panic, this expert advice will help you fix the problem

By Anna Cottrell published 21 December 21

'Why does my dishwasher smell bad?' is a question no one wants to be asking, given how essential the dishwasher is in any kitchen. A smelly dishwasher will put you off spending time in the kitchen, and worse, it will often make your dishes smell awful, which means you have to do them by hand. 

Even the best dishwasher can turn smelly if you don't maintain it properly, although there also are situations when a dishwasher begins to smell through no fault of the owner. Here are the most likely reasons why a dishwasher might smell bad, and how to fix the problem, according to an appliance expert.

This is by far the most common reason for a smelly dishwasher. Elyse Moody, appliance expert and head of content at Designer Appliances, puts it simply: 'A smelly dishwasher usually needs cleaning. Maybe it has been a little too long since you took out the filter and gave it a scrub.' 

Elyse acknowledges that some people may not even know that there is a removable filter in their dishwasher, because 'dishwashers used to have hard food disposals in the bottom that ground-up bits of food.' Newer machines, on the other hand, 'have filters that catch it instead. That's why you don't remember your mom ever cleaning the filter.'

If you're not sure where the filter is or how to remove it for cleaning, 'Just check your user manual to find out exactly how to remove it; usually it's in the bottom of the tub and you turn it and it slides out.' You can also consult our guide on how to clean a dishwasher filter for more help.

Elyse has a warning for anyone who didn't know there was a filter they need to clean: 'it might be really gross'. Make sure you're wearing gloves. 

Also gross but it does happen: 'bits of food can also clog up the utensil basket and the spray nozzles on the wash arms', Elyse explains. 'You can use a brush to clean those up'. 

This is where the good old argument about pre-rinsing comes in. Many people dislike the idea of pre-rinsing their dishes before putting them in the dishwasher, because it's extra work that the dishwasher should do. However, even the best modern dishwashers won't be able to cope with a constant buildup of food bits. If you can't be bothered to rinse the dishes, at least make sure you thoroughly scrape all food off the plates before putting them in. 

Learning how to clean a dishwasher regularly is also important. Even if you are very careful, small food particles will build up inside your machine over time.

Dishwasher not cleaning properly? If your dishwasher is generally clean and you maintain it well and it has begun to smell, Elyse points out that a potential reason is that 'your dishwasher's internal water filter system isn't that great or isn't working as well as it used to.'

Not all dishwashers have water filters, but if yours does and has been there a while, it may be that it's no longer filtering out the minerals found in hard water that form limescale and clog up pipes and other parts of your machine, including pumps, valves, and the impeller.

And yes, a dishwasher with limescale-clogged elements can get smelly. Fortunately, a dishwasher water filter can be replaced.

Installation errors do happen, and, as Elyse explains, 'sometimes if the drain hose isn't connected properly, dirty wash water can flow backward into your dishwasher. It could sit on the bottom of the tub and be stinky.' 

If your dishwasher is relatively new and it smells, this could well be the reason. If you don't understand which hose goes where, call your dishwasher supplier and ask them to send someone to check that it has been installed properly. 

If nothing seems wrong with your dishwasher but it still smells, you could have a more serious problem, i.e. a leak. If your dishwasher is leaking, it'll often go unnoticed until the leaking water has seeped through under the dishwasher. You may eventually notice that the area around the dishwasher, such as the bottom of a cabinet, is damp. 

A common reason for dishwasher leaking is a partial clog. Charles Leduc, Chief Operations Officer at Mold Busters, explains that 'we have had to remove mold from many kitchens due to homeowners continuing to run clogged dishwashers because they didn’t know they were partially clogged, and leaking out.'

If you think this is your issue, you'll need to call in a professional.

Apart from the ubiquitous clogged filter issue, a dishwasher that smells like rotten eggs (sulphur) could have a clogged garbage disposal hose. You'd have to disconnect your machine to see what's in there. 

Also, sometimes the smell of rotten eggs is actually the door gasket, that is the black rubber seal that keeps the dishwasher door hermetically sealed during dishwashing. Food particles can accumulate on the gasket over time, leading to a foul odor. Sears recommends wiping down the gasket 'with warm water periodically.'

This is a highly unpleasant problem that usually stems from a drainage issue and/or a partial clog. A dishwasher not draining properly will have standing water in it that is recycled by the dishwasher while you run it, imparting a stale odor that many people describe as a wet-dog smell. Unclog the dishwasher, run it on a maintenance cycle with some vinegar/bleach, and the smell will go away. 

Anna is Consumer Editor across Future's home brands. She moved to the world of interiors from academic research in the field of English Literature and photography. She is the author of London Writing of the 1930s and has a passion for contemporary home decor and gardening.

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