Inside the cistern there is an arrangement of pipework called the syphon. When the water enters the cistern, some of it enters the syphon through a one-way valve. When the toilet is flushed, the one-way valve actually lifts the water in the syphon up through the pipework and creates a syphoning effect which draws the remaining water from the cistern through the pipework. Simple and ingenious
Nobby, January 2009
