polite way is to say that you have to go to the bathroom.

Question: what the common and polite way is to say that you have to go to the bathroom.

Answer:
In the U.S., the most common terms are bathroom and restroom for the room with the toilet. In most U.S. homes, the room with the toilet is the same room where you’ll find the bathtub/shower and the sink. Even if it’s not, we still use these two terms.

The most common phrases we use are: “I need to go to the bathroom”/”I’m going to the bathroom” and the slightly more polite, “I need to go to the restroom”/”I’m going to the restroom.”

Other polite terms for the bathroom/restroom are the ladies’ room or the men’s room, and some women may use the terms powder room or the little girl’s room. However, “restroom” is fine in nearly all situations, so that’s the term I suggest using. In the U.S., you would very rarely hear anyone say, “I need to go to the toilet,” which is considered impolite and sounds a little strange to a native speaker, and Americans don’t use the terms “loo” and “W.C.” (water closet).

The most polite and formal ways to say you have to go to the restroom, however, does not mention the bathroom or restroom at all. At a formal gathering or at a business meeting, for example, most people would simply say, “If you’ll excuse me…” or “Excuse me” as they get up to go to the restroom.

In very, very informal situations, you may hear someone say, “I need to pee.” To pee is to allow urine (the water waste in your body) to come out. Again, this is very informal and impolite, so I don’t recommend ever saying this. I mention it in case you hear it in movies or on TV shows. Other very informal phrases you may hear are, “I need to go to the john.” The john is the toilet; and “I need to hit the can.” You guessed it–the can is the toilet.

I can’t believe I spent five paragraphs talking about the bathroom, but I hope this is helpful!