The cookware items you should never put in a dishwasher, according to an expert

Reckon you can clean just about anything in your dishwasher? Think again!

dishwasher with white bowl
(Image credit: Future PLC / David Giles)

The dishwasher is often a lifesaver for many homes – not only does it give us sparkling clean dishes and cutlery, but it also saves us precious time that would otherwise be spent hunched over the sink scrubbing.

But while it's super handy for ceramic dishes and silverware, did you know there are some things you should never pop in your dishwasher? While we all wonder how much it costs to run a dishwasher, you might not have considered this fact before.

Our dishwashers are actually not meant to accommodate all of our kitchen items. In fact, some of them can actually be damaged by being put through a washing cycle.

4 things you should never put in your dishwasher

1. Cast iron pots

The first item that should be reserved for hand-washing only, is any cast iron pots or pans you may have. 

These cookware items often have a rough patina/seasoning on the pan's surface, which can be ruined in the dishwasher. Joe Authbert, Buying Manager at ProCook, says, 'Instead, remove stuck-on bits of food by rinsing the cast iron pan with warm, soap-free water and a brush. Once your cast iron pan is washed, make sure it is completely dry, to keep the pan from rusting.'

ProCook Cast Iron pot

(Image credit: ProCook)

2. Kitchen knives

Now, we're probably all guilty of this next one; but Joe advises that you should also never put your kitchen knives in the dishwasher. Yes, really! Those quality chef knives should always be hand-washed.

'Dishwashers can have a devastating effect on the quality of kitchen knives,' he explains. 'They are abrasive and depending on the type of detergent used, the washing process can lead to rust or corrosion on the knife’s blade.' 

3. Thermal coffee cup

Another big no-no that may surprise you is putting your thermal coffee cups in the dishwasher. According to Joe, doing this could result in them losing their effectiveness. 

'After a wash in the dishwasher, travel mugs can lose their airtight properties.

'The insulated airspace keeping both cold and hot liquids at a consistent temperature can become compromised and lose efficiency,' he tells us.

Blue cabinets with dishwasher in kitchen

(Image credit: Future PLC)

4. Wooden chopping board and utensils

There's one final thing that should never wash in your dishwasher, and that's any wooden chopping boards or utensils.

While it means that we'll sadly have to spend more time hand-washing them, it's for the best, as the hot water and dry heat in your dishwasher can warp the wooden material, and even cause it to crack.

'A dishwasher can completely ruin a wooden kitchen product, and also make the wood appear dull,' Joe says. 

In order to keep your cutlery, glassware, and crockery looking their best while in the dishwasher, it's also important to take care of the actual appliance itself. Knowing how to clean a dishwasher is step one, closely followed by regularly adding dishwasher salt and Rinse Aid to it. 

If you follow these important steps, and keep the above essentials out of your dishwasher, both your cookware items and your appliances should stay in tip-top shape.


 Amy Hunt is an experienced digital journalist and editor, now working in a freelance capacity specialising in homes and interiors, wellness, travel and careers. She was previously Lifestyle Editor at woman&home, overseeing the homes, books and features sections of the website. Having worked in the industry for over eight years, she has contributed to a range of publications including Ideal Home, Livingetc, T3,Goodto, Woman, Woman’s Own, and Red magazine