Jeff's experience designing content solutions lead him to be one of our first contributors. He helped draft Makey's blueprint and is one of the best explainers of technical details we know.
While fill valve mechanisms inside a toilet have existed for over 100 years, its more modern concentric-float design has been around since the late 50s and is still growing in popularity because of its reliability.
The fill valve, which is a tower-like fixture inside the toilet tank, is responsible for filling and maintaining a predetermined amount of water inside the tank. There are two common types of fill valves, a side float design and a concentric float design. The side float design, commonly referred to as a ballcock, is easily identified by the float ball that is connected to the fill valve by a long (typically metal) arm. The concentric float design is identified by a float cup that travels up and down the shaft of the fill valve. With either type, the float rises as the water level increases to a set height/volume, closing the valve and preventing more water from entering the tank. There is also a less common floatless fill valve that uses a pressure sensitive diaphragm to sense the water level from the bottom of the tank.
If you’re hoping to avoid a costly plumber's bill, you’ll be happy to know that diagnosing problems with and replacing a fill valve is something most people can do themselves.