The wash room itself is two very tiny rooms, colored partially like the rest of the mansion, which has a general brown/white theme. The first room has inherited the mansion's coloration, whereas the second room has colors on the walls and floor not in any other part of the mansion. Inside is a bathtub which can be drained, to reveal the Phillips Head Screwdriver. It has two mirrors, one in each room, and a washing machine next to a sink. In Version 1, when the bathtub was drained, the dead body of Ryota is revealed, and the sound "bikkuri" was played. This sound was removed (but still can be found in the files) along with Ryota in all versions since.
Like the Bathroom, the wash room is a trap of sorts if you are being chased, as it's a tiny room with only one way in and out, along with the other room in the hallway that leads to it, so if you are being chased, do not head for that hallway unless you are confident you are at the end of the chase or can maneuver around The Oni to escape the hallway.