Toilet Fill Valve
A toilet fill valve performs the thankless task of refilling a toilet’s tank after each flush. They come in a variety of configurations, based on the size, shape, and design of the toilet. A malfunctioning one can make the toilet run continuously or fail to refill the tank with the right amount of water. When they’re installed too low in the tank, they can cause a cross-connection, where water that’s not safe to drink contaminates the drinking water. The one pictured here is too high for this tank. It might work fine, but no one can re-install the tank lid. Most people would find that unacceptable. Time to call a real plumber.