You're Better Off Putting These 11 Items in the Trash Than the Dishwasher

As a decades-long city dweller recently transplanted upstate, I’m the proud owner of my first dishwasher. My instinct has been to throw everything in its racks, but the practice has left me with cracked cutting boards and broken glass.

A dishwasher’s scorching heat and powerful blasts of water are what get most items really clean. On the other hand, those features can warp, shatter and otherwise damage your fragile and porous kitchenware.

Before running the next power cycle, double-check the items you’re sticking in the racks. Your favorite chef’s knives, frying pans and stemware will thank you.

11 things your dishwasher will destroy

1. Insulated mugs

The high heat and pressure of a dishwasher can damage or break the vacuum seal that makes these insulated vessels effective. Instead, wash them by hand using warm water and soap. 

2. Wooden cutting boards

Wood cutting boards can become damaged after even one cycle through the dishwasher. Hot water can cause even the strongest wood to warp, bend, crack or split. While plastic and stone cutting boards can typically be handled in the dishwasher, wooden slabs should be washed by hand and dried thoroughly on their side. 

Read our guide to wooden cutting board care for more. 

3. Wine glasses 

Ninety % of wine glasses are not dishwasher safe. If you have thick, sturdy glasses, they may fare OK, but thin and delicate wine glasses are likely to break. Instead, wash them by hand and be sure to rinse them well so there’s no soapy residue messing with your next wine’s balanced bouquet. 

4. Kitchen knives

If you’ve got a sharp chef’s knife and want to keep it that way, keep it out of the dishwasher. Not only will extended soaking in hot water compromise the blade’s edge, but the dishwasher could also cause your knife to clank about and knock into other items, which will ding and dull the blade. 

Here’s a list of other bad habits that are ruining your knives. 

5. Antiques, porcelain and fine China

Antique cookware, bakeware, and glassware aren’t good candidates for the dishwasher. Even if it’s labeled “dishwasher-safe,” it’s age may have compromised a once rugged integrity, making it prone to chipping or cracking. If you have vintage cookware, kitchen tools or China you love, protect them by hand washing in the sink.

While porcelain itself is dishwasher safe, porcelain wares are often thin and brittle, and running them through the dishwasher puts them at risk. 

6. Nonstick cookware

Most nonstick cookware is technically safe to load into the dishwasher, but that doesn’t mean it’s a good idea. Nonstick surfaces are easily scratched and eroded when pummeled with hot water and soap or rubbed and knocked against other pots, pans or plates. 

7. Copper cookware

While I don’t recommend putting any good cookware in the dishwasher, copper cookware is particularly susceptible to damage. Copper will dull and tarnish from long exposure to hot water and the metal is soft, making it vulnerable to dings and dents if knocked against other items in the rack. 

8. Cast-iron cookware

You’ve worked so hard to build up a layered seasoning and slick patina on your cast-iron skillet, and one cycle through the dishwasher has the potential to strip it all away. Harsh dish detergent is likely to wreak havoc on the surface, while extended soaking in hot water can cause rust. Instead, use this pantry staple to clean stubborn cast-iron pans. 

9. Greasy plates and pans

Your instinct when confronted with a greasy, oily pan may be to huck it in the dishwasher and hope for the best. Oil and grease are notorious for causing clogs in dishwashers — and sinks for that matter. 

Instead, try to discard as much of the oil as possible into the trash with a scraper or paper towel and hand-wash your oily cookware well with soap and hot water. Only then, when most of the grease is removed, should you consider running it through the dishwasher.

10. Wooden utensils

Anything made from wood can be ruined if run through the dishwasher. That includes cooking utensils, spoons, chopsticks, bowls and anything else. Wooden items should always be hand-washed and dried quickly and thoroughly to avoid splitting, warping and bacteria growth.

11. Plastic cups and containers

Acrylic bowls and other sturdy plastics are fine to run through the dishwasher, but flimsier plastic containers are not. Most takeout boxes and food storage containers will melt when hit with boiling hot water. Plastic cups are also susceptible to melting and should be washed by hand instead.