A toilet works because of gravity. When a flush lever is pulled, a plug opens, allowing water to flow out to fill the basin. When the basin is full enough, gravity causes the liquid to flow out through a bend in the pipe, called an S trap.

Are older toilets better?

The biggest difference between older toilets and the models available today is the amount of water they use. Toilets manufactured after 1992 need less than half as much water per use as many older units, while providing a better flush and new convenience features.

How does a toilet without a cistern work?

In simple terms this is like emptying half a bucket of water from the side of the rim into the bowl. With the cisternless design, the flush process is powered by the mains water pressure. The mains water pressure is usually around 400kPa. This is like holding a fully opened garden hose into the toilet bowl.