In Canada and the US it is impolite to use the word toilet. You can call the actual physical thing a toilet, but if you want to say that you need to use the toilet, you must say something else.
We have all sorts of other polite names for it! You can start by saying:
Where is the _________ ?
I need to use the _________.
I have to go to the __________.
Then, you can choose one of the following words, based on where you are:
restroom – in the US, in a public place
washroom – in Canada, in a public place
ladies’ room or men’s room – in a public place
bathroom – in someone’s house
In the construction, real estate, and interior design professions, there are two formal names for different types of bathrooms in a house:
powder room: a small bathroom with only a toilet and a sink (but with no bathtub or shower)
en suite: a full bathroom connected to a room
bathroom: a room with a toilet, a sink, and a bathtub and/or a shower, but not connected to a room
IMPORTANT: You may have learned some other slang words for toilet, but you must remember that those words are slang and should NOT be used in public or in a professional environment, especially with people you don’t know.