There is a laundry in Hogwarts Castle. It is presumably run by house-elves.
History
In 1992, Hermione Granger snuck three Slytherin robes from the laundry, in order for Harry Potter and Ron Weasley to be dressed as Slytherin students when they had drunk the Polyjuice Potion.
Appearances
- Harry Potter and the Chamber of Secrets (film)" (mentioned in deleted scene)
- "Harry Potter and the Chamber of Secrets" (mentioned only)