Press the handle to flush the toilet and you operate a lever (dotted line) inside the cistern.
The lever opens a valve called the flapper (green) that allows the cistern to empty into the toilet bowl beneath through a mechanism called a siphon.
Water flows from the cistern through holes in the rim so it washes the bowl as well as flushing the contents away.
There's enough water flowing down from the cistern to flush the toilet around the S-bend (S-trap). This produces a siphon effect that sucks the bowl clean. It also ensures some water remains at the bottom of the toilet, which improves hygiene.
The contents of the toilet are flushed down the main drain.
As the cistern empties, the plastic float (red) falls downward, tilting a lever.
The tilting lever opens the ball valve(ball cock) (green) at the base of the cistern (or on one side of it), which works a bit like a faucet (tap). Pressurized water flows in, refilling the cistern, and pushing the float back up again. When the float reaches the correct level, the ball valve switches off the water supply and the toilet is ready to flush again.
