Toilet Functions

A flush toilet disposes of our waste products by using water to send them through a drainpipe to another location. It is sometimes called a water closet, or WC.

The picture below shows a typical toilet. The toilet bowl usually has a ring-shaped seat on top, which is covered by the lid when not in use.

The handle’/button, is pressed to flush the toilet. The water used for flushing is stored in the tank (also called a cistern)

Main parts of a toilet

The tank contains some important parts. The next picture shows the parts of a typical tank. The inlet valvecontrols the water supply coming into the tank. It lets water in when the tank is empty, and stops water coming in when the tank is full.

The “‘float ball”‘ rises as the tank fills with water. As it rises, the float rod attached to it presses against theinlet valve. When the tank is full, the rod is pressing against the inlet valve hard enough to turn the water off. This stops the tank from overflowing.

Parts of a typical toilet cistern

When you press the handle, a lever inside the tank pulls the piston up, forcing some water through thesiphon. This provides suction in the siphon, and the rest of the water follows, emptying the tank.

A toilet cistern emptying

The tank empties quite quickly, and the float ball floats to the bottom. That means the float rod is no longer pressing against the valve, so water begins to flow into the tank, filling it up again.

A toilet cistern empty

The water which left the tank goes through a short pipe to the toilet bowl. It sloshes around the rim, down the sides of the bowl, and out through the drainpipe, cleaning the bowl and carrying the waste with it.

Arrows showing the way water flows from the cistern, through the toilet bowl, and out.

Some of the clean water coming behind remains at the bottom of the toilet bowl. That’s because modern toilets have an ‘S’ bend which remains filled with water between flushing. The water in the ‘S’ bend stops bad odours escaping from the drainpipe. During flushing the ‘S’ bend also provides siphon action which helps speed up the flushing process.

However, since this type of toilet does not generally handle waste on site, separate waste treatment systems must be built.