2 Different Types of Toilet Fill Valves Explained

The inside of a toilet tank

If you are repairing, upgrading, or installing a toilet, you will probably need to think about your toilet fill valve. Toilet fill valves control the amount of water that is used whenever your toilet is flushed, preventing your toilet from overflowing, using too much water, or not using enough water to work properly. While toilets can function in a wide variety of ways, particularly when you consider the fact that the way toilets work has changed over time, there are really only two basic types of toilet fill valves that encompass all different models. What follows should explain the basic differences between the types of toilet fill valves.

Float Ball

toilet float ball in a toilet tank

Float ball type fill valves are an older model of fill valve. Also known as ballcock fill valves, they are not commonly built into new toilets, but you will see them very often in older models of toilet.

A toilet controlled by a float ball fill valve contains a plastic or rubber ball full of air on the end of a metal arm. This ball floats on the surface of the water in the toilet tank. When the toilet flushes and the water leaves the tank, the ball moves down with the surface of the water. When the tank is refilled, the ball moves back up. When it reaches a certain point, it triggers the valve that shuts off the flow of water.

Float ball type fill valves have few disadvantages compared to the newer float cup fill valves. The main downside to a float ball type fill valve is that it takes up more space. Other than that, they are perfectly good at regulating the amount of water that is used each time your toilet flushes. In fact, they may be easier to modify due to their simple design and bendable arm. However, the amount of space they require may actually prevent you from installing one in a newer toilet designed with the exact amount of space for a float cup valve. They may also be difficult to find replacement parts for.

Float Cup

toilet tank with blue dye

In contrast with float cup type toilet fill valves, float cup type fill valves are more modern. Generally speaking, new toilets that are constructed today will use float cup fill valves to control the amount of water a toilet uses.

Float cup fill valves use the same overall principles to keep a toilet functional that float ball fill valves do. In float cup fill valves, a cylindrical float surrounds a smaller cylinder. The float can move up and down freely as the water in the toilet tank rises and falls. When the float is below the intended water level, the valve opens and the toilet tank refills. However, this raises the water level, causing the float to rise. Eventually, the float rises again to the intended water level, which shuts off the valve.

While float cup fill valves are not particularly different than float ball fill valves, they do have a few advantages. In addition to their smaller size, they generally require no special tools to adjust up and down.