A ballcock. which is also known as a fill valve, is a mechanism for filling water tanks. Usually the ones found in flush toilets, while avoiding any overflow. This was invented by Thomas Crapper.
There is a float valve, connected to a lever at the top of the tank. This is connected to the water supply, and is opened or closed by the lever. When the water level rises to the preset line, the valve closes and shut off the water flow.
Did you know?
There are some urinals with fake house-flies or bumblebees imprinted on them. Manufacturers have found that restrooms stay cleaner when men have something to aim for.