That’s a useful topic, but it’s often used as clickbait. In reality, dishwashers are great—but some items really do get damaged by heat, water pressure, or detergents.
Here are 8 things you should usually NOT put in a dishwasher, and why:
🪵 1. Wooden utensils & cutting boards
- High heat and water cause warping and cracking
- Wood absorbs moisture and can split over time
🔪 2. Sharp knives (chef knives)
- Dishwasher detergents can dull the blade
- Knives may knock against other items and lose sharpness
🍳 3. Non-stick pans
- Heat and detergents can damage the coating
- Once scratched, the non-stick layer breaks down faster
🍷 4. Delicate glassware or crystal
- Can become cloudy or etched
- Fragile items may chip or crack
🍴 5. Cast iron pans
- Dishwasher removes the protective seasoning
- Leads to rust and loss of non-stick surface
🥄 6. Insulated travel mugs / thermoses
- Can damage vacuum seals
- Reduces insulation performance
🧴 7. Sharp or fine-edged plastic containers
- Heat can cause warping or chemical breakdown
- Especially low-quality plastics
🍯 8. Hand-painted or decorative items
- Designs can fade or peel
- Glaze may degrade over time
🧠 Bottom line
Dishwashers are safe for most modern kitchenware, but:
Heat + pressure + strong detergent = damage to certain materials over time.
If you want, I can also give you a “dishwasher-safe vs not safe” quick cheat sheet for everyday items.
