[2][3] It consists of a valve connected to a hollow, sealed float by means of a lever mounted near the top of the tank.
When the handle of a flush toilet with a tank (British, cistern) is turned, a discharge mechanism is activated by means of a rod or chain.
Water is fed to the tank to replenish its supply, and a smaller flow is directed into the overflow tube to refill the bowl.
Typically the fill valve is secured by a ballcock shank washer, which prevents leakage from the supply line.
This design uses a ballcock attached to a pivoting lever that opens and closes a plunger stem fitted with a washer that seals against a water inlet port.