How Does a Wall-Hung Toilet Work?

Wall-hung toilets offer a small silhouette and tidy appearance. Don't let the lack of a visible water tank fool you, though -- wall mounted toilets simply hide much of their bulk between the wall studs behind them. Though initial installation is more complex than that of a standard toilet, this toilet style saves space and allows for easier floor cleaning.

Man cleaning toilet
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Wall-hung toilets take up less space in small bathrooms.

Water Tank

The apparent lack of a tank is the first thing most people notice about a wall-mounted toilet. In fact, wall-hung toilets use the same gravity flush system as a normal commode. The slender water tank is mounted on a sturdy metal frame that connects to studs in the wall, which is then finished around the various pipes and controls for the toilet. To prevent tank freeze-up, wall hung toilets should not be placed on exterior walls in cold climates.

Bowl Mounting

The same metal frame that holds the water tank also supports the bowl, which does not touch the floor. Two strong, threaded rods screw into holes in the frame at a convenient height. The wall is finished around them, and the flat-backed bowl assembly slides over the rods and is bolted into place. Adhesive on the back of the bowl lends an additional layer of support, and a line of caulk around the outside prevents moisture from getting into any crevices between the bowl and the wall.

Flush Mechanism

Because the tank is hidden, wall-hung toilets have no lever for flushing. Instead, a button on the wall above the bowl connects by means of an actuator to a valve in the inlet pipe inside the wall and above the water tank. Some models have two buttons controlling two flush modes; one using more water and one using less. These different flush modes, labelled "full flush" and "low flush," are used as a water-saving measure.

Drainage Pipe

In a normal toilet, the drainage pipe leads down through the floor at the base of the bowl and into the home's drain system. In a wall-mounted toilet, the drainage pipe comes out of the back of the bowl near the bottom, joining up with the drain system via a pipe in the wall. This pipe travels down through the wall's base plate in most cases, though it is possible to hook into a horizontal drain pipe in the wall, as well.