One Room, Many Incarnations
The modern water closet, commonly known as a powder room, consists of a toilet and a sink. In US.
home design, elements of old-world thinking regarding the placement of the water closet still exist -- a discrete placement in a hallway on the first floor near the home's entrance. But some full bathrooms feature water-closet elements within them, such as a partition separating the toilet from the sink and the bathtub area, or a door separating the toilet and sink from the larger bathroom area.
Some manufacturers use the term "water closet" for the toilets they produce, referencing that the fixtures can be used in both residential homes and public buildings; public restroom stalls most closely resemble the old water closets. The Americans With Disabilities Act compliance guidelines also refer to toilets designed for use by those with physical challenges as water closets.