The design of a bathroom must account for the use of both hot and cold water, in significant quantities, for cleaning the human body. The water is also used for moving solid and liquid human waste to a sewer or septic tank. Water may be splashed on the walls and floor, and hot humid air may cause condensation on cold surfaces. From a decorating point of view the bathroom presents a challenge. Ceiling, wall and floor materials and coverings should be impervious to water and readily and easily cleaned. The use of ceramic or glass, as well as smooth plastic materials, is common in bathrooms for their ease of cleaning. Such surfaces are often cold to the touch, however, and so water-resistant bath mats or even bathroom carpets may be used on the floor to make the room more comfortable. Alternatively, the floor may be heated, possibly by strategically placing heater conduits close to the surface.
Electrical appliances, such as lights, heaters, and heated towel rails, generally need to be installed as fixtures, with permanent connections rather than plugs and sockets. This minimizes the risk of electric shock. Ground-fault circuit interruptor electrical sockets can reduce the risk of electric shock, and are required for bathroom socket installation by electrical and building codes in the United States and Canada. In some countries, such as the United Kingdom, only special sockets suitable for electric shavers are permitted in bathrooms, and are labelled as such.