Why does my toilet keep running?

Recently a customer asked us, “Why does my toilet keep running?” In order for the answer to this question to make sense, it helps us to first understand how a toilet works. This is our second entry in our new blog series entitled “Plumbing Knowledge from a Pro”.

How a toilet works

A toilet consists of a tank and bowl. On the outside of the tank you can find the flush handle (or sometimes a button). The inside of the tank is where the magic happens. The tank houses a flapper, fill valve, flush valve, float and overflow tube. When we press the flush handle on the tank, it is connected by a chain to a flapper that lifts and opens the passageway for fresh water to flow from the tank into the bowl. As the fresh water leaves the tank, the flapper falls back into the closed position and it stops the water from leaving the tank and entering the bowl. Once the tank has emptied its fresh water into the bowl, the contents of the bowl are flushed with the help of gravity through the S trap of the toilet and down the drain. Fresh water enters the tank from the supply tube into the fill valve and continues to enter the tank and bowl until the float reaches a preset level. Once the float reaches a predetermined level the fill valve closes and fresh water stops entering the tank. Now the tank and bowl are filled with fresh water ready for the next flush.

Our friends at Korky have provided the following video detailing the anatomy of a toilet and how they work.

Reasons a toilet keeps running

That is the way a toilet is supposed to work. Since flappers are made of a rubber like material, overtime they can warp, change shape, or degrade. If a flapper can no longer maintain its shape then it probably can’t seal the fresh water opening between the tank and bowl as it is supposed to. This is why you may see water “moving” or rippling” in the toilet bowl. If you see water moving or rippling in the toilet bowl after it has filled you can probably bet your flapper needs replaced.

If you continue to hear water running but you don’t see water moving or rippling in the toilet bowl itself then you may need to adjust your float. The float is attached to the fill valve and it can often be adjusted to a specified height that causes the fresh water fill valve to close and fresh water to stop entering the tank. If you suspect this type of problem, your float can be adjusted by turning a small adjustment screw at the top of the fill valve to raise or lower the float. If by contrast you have a ball type valve, you may need to bend the metal bar that is attached to the ball upward or downward to stop the water from entering the tank.

If you have never looked inside your toilet tank it is worth a look. Having a basic understanding of its operation can save you a lot of money in the long run and help you understand the type of problem you may be encountering. If you have tried these suggestions, but still need help please give us a call, we would love to help.

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