Welcome to Toilet School
As simple as toilets may seem, they can be quite complicated!

Most people are familiar with the basic components that make up the outside of a toilet – the tank, bowl, flush handle, etc. – but what are the parts inside of the tank? What do they mean? What do they do?

If you want to learn more about the ins and outs of your toilet, then you’ve come to the right place!

The Different Parts of a Toilet

Inside your tank, there are six main components that allow your toilet to function properly:

Diagrams of Different Toilet Tanks
1. Handle: Located on the outside of the tank. Pushing it down will start the flush cycle. Newer toilets may have a button or touchless sensor.

2. Lift Chain: Connects the handle to the flapper. Pushing down on the handle raises the flapper off the flush valve.

3. Flapper/Flush Valve: The flapper is the round, rubber device positioned on the bottom of the toilet tank covering the flush valve. When the handle is pushed down, the flapper opens, allowing water from the tank to rush into the bowl (through the flush valve). After the flapper closes onto the flush valve, the tank and bowl refill with water.

4. Float (ball or cup type): Controls the opening and closing of the fill valve. As the water height drops in the tank, the float opens the fill valve. As the water rises, the float closes the fill valve.

5. Fill Valve: Controls water flow into both the toilet tank and bowl. The fill valve has upper and lower ports which open and close simultaneously. The lower port refills the tank, while the upper port refills the bowl through the overflow tube by way of the refill tube.

6. Overflow Tube: During normal function, water from the fill valve flows through the overflow tube in order to refill the toilet bowl. However, if the fill valve does not shut off properly and contines to fill the tank, excess water will drain through the overflow tube into the bowl.

What is a Flush Cycle?

The flush cycle is the time it takes for the toilet to clear waste from the toilet bowl and refill with water.  The flush cycle can be broken into two phases – evacuation and refilling – with a brief (1-3 second) pause between each phase.  Depending on the model of toilet, water pressure, and how well your toilet is working, the flush cycle can be as short as 15 seconds to as long as two minutes.

The evacuation phase begins when you push the flush handle (or button).  This lifts the flapper and opens the flush valve, allowing water to rapidly evacuate from the tank and into the bowl.  The force of the evacuating water creates a siphon effect, pulling the waste from the bowl and into the drain.  The float, which rises and falls with the water height in the tank, drops to the lowest point in its cycle.  When this occurs, the fill valve turns on, beginning the refill phase.

The refill phase begins when the flapper drops, closing the flush valve.  The lower port of the fill valve begins to fill the tank with water, causing the float to rise.  At the same time, the upper port of the fill valve refills the bowl through the overflow tube.  Once the water height raises the float to the top of its cycle, the float closes the fill valve with a “snap action”.  The tank and bowl are refilled with water, and the toilet is ready for another use.

What is a “Phantom Flush”?

Have you ever heard your toilet periodically make a noise that sounds like the water is running, but it hasn’t been flushed recently? What you’re hearing is called a phantom flush, the unintended and unseen escape of water from a toilet that is not operating correctly.

A phantom flush occurs when water leaks from the tank into the bowl due to a faulty flapper (or another similar failure). As the water level inside the tank goes down, the float drops. This opens the fill valve briefly, allowing it to refill the partially empty tank.

If the failure causing the phantom flush is not corrected, a repetitive cycle of leak…fill…leak…fill is created. This cycle can waste 50 – 200 gallons of water every day, making leaking toilets the #1 cause of unintended water use in the home.

Diagram of a toilet with phantom flush

What causes a “Phantom Flush”?

Below is a list of reasons why the repetitive “Phantom Flush” cycle can occur.

  • Flapper is not sealing properly because:
    • It’s the wrong size or model for your toilet.
    • Something is stuck under the flapper lip.
    • It has deteriorated or warped from hard water and/or cleaning solvents.
    • It is physically defective.
    • It has a pinhole in it.
  • The chain is not working properly because:
    • It’s too short and holds the flapper open slightly
    • It’s too long and gets stuck under the flapper
    • It gets kinked and holds the flapper open
  • The fill valve stops working correctly (leaks or doesn’t fully close)
  • The float height is set improperly
  • Fluctuations in water pressure throughout the day