Think twice before loading everything into the dishwasher. While it might seem like the quickest way to clean up after cooking, some kitchen items should never go in – and doing so could damage your cookware, ruin finishes or even lead to expensive appliance repairs.
Below, we reveal the items you should always keep out of the dishwasher, plus the safest way to clean them instead.
1. Wooden chopping boards and utensils
Putting wooden chopping boards, spoons and bowls in the dishwasher is one of the quickest ways to ruin them. The combination of high temperatures, prolonged moisture and powerful detergents can cause wood to crack, warp and splinter, significantly shortening its lifespan.
‘Dishwasher detergents strip away the natural oils in wood, making items brittle,’ says Adam Norris, dishwashing and laundry expert at Hotpoint. ‘Any cracks that form become breeding grounds for bacteria, which defeats the purpose of cleaning them in the first place.’
To keep wooden kitchenware in good condition, wash it by hand using warm, soapy water and dry it immediately afterwards. Avoid leaving items to soak, as excess moisture can cause further damage. For stubborn stains or lingering odours, sprinkle salt over the surface and scrub with half a lemon before rinsing – it's a simple natural cleaning hack that helps freshen and deodorise wood.
2. Non-stick pans and bakeware
If your once-reliable non-stick pan has started causing food to stick, your dishwasher could be to blame. Frequent dishwasher cycles can gradually wear away the non-stick coating, thanks to high temperatures and harsh detergents, leaving cookware less effective and more prone to damage.
‘Once the non-stick surface deteriorates, your next omelette will stick to the pan,’ reveals Adam. ‘Those flakes can also clog your dishwasher filter too, creating an unnecessary maintenance issue.’
While some modern non-stick cookware is labelled dishwasher safe, it's always worth checking the manufacturer's instructions before loading it in. To help extend the lifespan of your pans and bakeware, wash them by hand using warm water, mild washing-up liquid and a soft sponge. Avoid abrasive scourers, which can damage the protective coating even faster.
3. Delicate glassware
It may be tempting to put your best wine glasses straight into the dishwasher, but delicate glassware can easily become damaged. Fine crystal, antique glasses and older stemware are particularly vulnerable to chipping, cracking and clouding when exposed to high temperatures and repeated dishwasher cycles.
‘Modern dishwashers often include glass care or delicate settings designed to protect more fragile items,’ explains Adam. ‘However, for particularly valuable or sentimental pieces, hand washing is still the safest option.’
To help preserve delicate glassware, wash it carefully by hand using warm water, mild washing-up liquid and a soft cloth. If you do use a dishwasher, place glasses securely on the top rack so they don't touch one another, and select a low-temperature or dedicated glass programme to reduce the risk of damage and keep them sparkling for longer.
4. Sharp kitchen knives
While many stainless steel and ceramic knives are technically dishwasher safe, that doesn't mean they belong in the dishwasher. Repeated exposure to high temperatures, strong detergents and prolonged moisture can dull blades more quickly, leaving them less effective and requiring more frequent sharpening.
‘The wash cycle can also cause blades to knock against other items, damaging the edges of your knives,’ says Adam.
Fortunately, knives are one of the quickest kitchen items to clean by hand. Simply wash them with warm, soapy water and dry them immediately afterwards. Taking a few extra seconds to hand wash your knives will help keep blades sharper for longer, improve cutting performance and extend the lifespan of your kitchen tools.
5. Cast iron cookware
Cast iron cookware should never go in the dishwasher. One of its biggest benefits is the protective seasoning layer that develops over time, created by baked-on oil. This natural coating helps prevent food from sticking and protects the metal from rust.
‘Dishwasher detergent strips this away completely, leaving bare metal that will rust quickly,’ explains Adam. ‘Even enamelled cast iron can become dull and damaged in the dishwasher.’
To keep cast iron cookware in top condition, wash it by hand and dry it thoroughly straight away to prevent moisture from causing rust. For added protection, apply a thin layer of neutral oil, such as rapeseed or vegetable oil, while the pan is still warm. This simple maintenance step helps preserve the seasoning, maintain its non-stick properties and extend the life of your cookware.
6. Insulated travel mugs and bottles
If your coffee is going cold too quickly, your dishwasher could be the reason. Insulated travel mugs and water bottles rely on a vacuum seal to keep drinks hot or cold, but repeated exposure to high dishwasher temperatures can permanently damage that seal.
‘Once that seal is compromised, the insulation becomes ineffective, and leaks can develop,’ explains Adam. ‘Many travel mugs also have rubber seals on lids where water can become trapped, creating the ideal environment for mould to grow.’
Always check the manufacturer's care instructions first, as some newer stainless steel models are dishwasher safe. If yours can go in the dishwasher, place it on the top rack for a gentler clean. Otherwise, wash travel mugs and bottles by hand with warm, soapy water, paying close attention to lids, seals and drinking spouts where residue and moisture can build up.
7. Antique or hand-painted items
Whether it's a treasured charity shop find, a family heirloom or a hand-painted plate you've created yourself, decorative pieces should be kept well away from the dishwasher. The combination of hot water, powerful detergents and prolonged wash cycles can cause delicate finishes to fade, crack or peel over time.
‘The combination of high heat and detergent in a dishwasher cycle can fade patterns, chip away decorative paint and strip gold leaf,’ warns Adam.
To preserve both the appearance and value of these special items, wash them gently by hand using warm water, mild washing-up liquid and a soft cloth. Avoid stacking pieces together while cleaning, as this can increase the risk of chips and scratches. For stubborn stains, use a small amount of baking soda on a damp cloth and gently buff the affected area without scrubbing too hard.
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