Here's proof that even a sliver of space can work as a bathroom, concealed behind closet style doors or a simple sliding door.
Above: A bathroom housed behind a wall of closet doors in a renovation by Studio Ina Matt (also see Architect Visit: Studio Ina Matt in the Netherlands).
Above: A bathroom concealed behind sliding doors in a project by SF architect Christi Azevado (see Architect Visit: 28th Street Carriage House by Christi Azevado).
Above: A bathroom by Texas architect Max Levy (also see Architect Visit: Max Levy in Dallas).
Above: Another bath tucked into a closet space from Studio Ina Matt, this time without doors.
Above: A bath in the Netherlands via Elle Wonen.
Above: A bath at the Lloyd Hotel in Amsterdam.