Category: 

What Is a Ball Cock?

A ball cock in a toilet controls how much water is in the tank.
Article Details
  • Written By: Autumn Rivers
  • Edited By: Andrew Jones
  • Last Modified Date: 16 October 2014
  • Copyright Protected:
    2003-2014
    Conjecture Corporation
  • Print this Article
Free Widgets for your Site/Blog
In 18th-century England, murderers could ask for a lesser sentence by claiming a full moon made them act erratic.  more...

November 20 ,  1945 :  The Nuremberg Trials began.  more...

A ball cock, or fill valve, is the part in a toilet that controls the amount of water in the tank. Its job is to ensure that the right amount of water is in the tank so that the toilet does not overflow when the lever is pushed. As the name indicates, this item is made up of a hollow ball, which is attached to a lever that affixes to the rest of the toilet mechanism. It is mounted near the top of the tank. The ball cock is usually made of either metal or plastic, and can usually be easily replaced when necessary.

The mechanism is made up of a ball that floats in the water, which is affixed to a long lever. This lever attaches to a valve that is connected to the piece that houses the incoming supply of water. When the water reaches a certain line near the top of the tank, the float rises enough to force the lever to close the valve, which stops the flow of water. Thus, a broken ball cock may result in the toilet either overflowing, or even just slowly leaking excess water into the bowl, wasting it. Fortunately, this piece of equipment is usually quite inexpensive, and can be found at most home improvement stores.

Ad

It is best to understand how a toilet works, and how the ball cock fits into the mechanism, before repairing this part. When the toilet is flushed, a chain usually pulls the flapper valve upward, which will then gradually sink slower than the water level does. Once the water from the tank is emptied into the bowl, the floating ball slowly lowers until the fill valve is activated, causing the water to gradually fill the tank once more. At the same time, the overflow tube slowly fills up with a small stream of water to feed into the bowl until the right amount of water is present. When the flapper valve is closed, the fill valve will continue to allow the flow of water until the tank's level is replenished.

The ball cock can be found in either metal or plastic, and either type can be used as long as the threaded shank matches the old one. In fact, it is helpful to bring the old ball cock when purchasing a new one to make sure that it will be compatible with the toilet. It should be noted that while the plastic type is cheaper and will not corrode, it is not usually as sturdy as the metal kind.

Ad

More from Wisegeek

You might also Like

Discuss this Article

Laotionne
Post 2

I know a lot of people do bend the ball cocks when the water continues to run, but you're not supposed to do that. It damages the ball cock assembly over time. There should be a couple screws, or maybe only one screw, that you can tighten and loosen to change the angle of the ball cock.

Animandel
Post 1

One of the most vivid memories I have of my first apartment is the bathroom. The toilet never stopped running and the noise was really irritating. At that time, I had no experience working on much of anything. My father always made repairs in our house. My roommates and I lived with the running toilet for months. For some reason, we were afraid the landlord would think we were being a nuisance if we mentioned it and asked him to repair it.

Finally, I went into the bathroom one day, lifted the lid off the toilet tank and studied the set up until I figured out that all I had to do was bend the arm attached to the big ball. I felt so silly for not doing it sooner. I had heard the term ball cock before, but I didn't know exactly what it was until reading this article. We just called it the ball thing in back of the toilet.

Post your comments

Post Anonymously

Login

username
password
forgot password?

Register

username
password
confirm
email