A push button toilet cistern works through the combination of a plastic float and a central plastic outlet valve water supply line. Usually, push button cisterns have two button options for increased water management. The smaller button uses the least amount of water per flush and operates the plastic float.
When the smaller button is pressed, the float is driven down, which opens the valve and allows water to rush out of the cistern and into the toilet bowl. When the button is released, the float rises and closes the valve again. When the larger button is pressed to release a greater amount of water, a lever is lifted in the central flushing mechanism and locks into place, which holds the cistern valve open. This a larger amount of water to fill the toilet bowl even after the flush button has been released. Once the water has exited the cistern, the lever releases within the central flushing mechanism and allows the valve to settle back into place. The cistern then fills via the water supply line until the next time the toilet is flushed. A large flush for a button toilet usually uses about 6 liters of water, whereas the smaller flush uses between 3 and 4 liters.