Machine dishwashing
Hot, strongly alkaline and unattended. It is the most aggressive routine cleaning most households own, which is why so many things are excluded from it.
What not to do
Machine dishwashing is unsafe on Detergent drawer
Unsafe
Do not do this. The risk is established, and it is described below.
A removable plastic part that looks obviously dishwasher-safe, and is not.
Evidence
Supported
Sources
How to Clean a Front Load Washer Dispenser (Drawer)
Whirlpool Corporation · Manufacturer documentation
Relied on for: That the dispenser drawer is removed and washed under warm running water with a soft brush, that the housing is cleaned with mild soap and a soft cloth, and that removable parts must not be cleaned in the dishwasher. (states this directly)
Machine dishwashing is unsafe on Cast iron pan
Unsafe
Do not do this. The risk is established, and it is described below.
Evidence
Strongly supported
Sources
How to Clean seasoned cast iron
Lodge Cast Iron (Lodge Manufacturing Company) · Manufacturer documentation
Relied on for: That a dishwasher will remove the seasoning from cast iron and will likely cause rust. (states this directly)
Precautions
- Check the manufacturer's instructions
In detail
A dishwasher cycle is not a gentler version of washing up. It combines a strongly alkaline detergent, water hotter than hands tolerate, and prolonged mechanical spray, and it runs for over an hour with nobody watching. A food-safety regulator recommends it over hand washing for exactly those reasons — it washes at a high temperature and does the job thoroughly. The same properties are why the exclusions are so long. Aluminium is attacked by the alkalinity, decorated glaze is etched, wooden handles dry and split, and manufacturers exclude specific removable plastic parts from it in writing even when those parts look obviously suitable. A washing machine's dispenser drawer is one: removable, plastic, and prohibited. The useful habit is to treat 'dishwasher safe' as a claim requiring evidence rather than a default. The absence of a prohibition is not a permission, and for appliance parts the manufacturer's own documentation is the only thing that settles it.
What works
Machine dishwashing is safe on, in specific conditions, Fridge shelf
Safe only in specific conditions
This is only appropriate within specific limits, and nothing is established outside them.
Only within these limits:
- Only where the refrigerator's own manufacturer says its shelves are dishwasher safe
- The shelf must reach room temperature first
- Handwashing remains that manufacturer's preference
One manufacturer's FAQ, for its own shelves. A permission and a preference, and the room-temperature rule survives both.
Precautions
- Check the manufacturer's instructions
Evidence
Supported
Where sources disagree
The same maker forbids the dishwasher for a washing machine's dispenser drawer, another removable plastic part. Dishwasher permission is set part by part and maker by maker.
Sources
Cleaning the Interior of the Refrigerator
Whirlpool Corporation · Manufacturer documentation
Relied on for: That glass shelves and bins are dishwasher safe but handwashing is recommended, and that they must reach room temperature first. (states this directly)
Sources for this page
Sources
How to Clean a Front Load Washer Dispenser (Drawer)
Whirlpool Corporation · Manufacturer documentation
Relied on for: That the removable dispenser parts must not be cleaned in the dishwasher and must be washed only by hand. (states this directly)
Safe Method: Cleaning Effectively (Safer Food, Better Business)
Food Standards Agency, United Kingdom · Government or regulator
Relied on for: That a dishwasher washes items thoroughly at a high temperature and is a good way to clean equipment, and that it must not be overloaded or items will not wash effectively. (states this directly)