How Does a Toilet Tank Work?

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How Does a Toilet Tank Work?

When it comes to home repair, toilets may fall in the “easy fix” or “emergency plumbing” arenas. The good news is: you can easily break down what’s going on. A lot of times, it’s what’s going on inside. With just a quick jiggle of the handle you may realize that the issue is inside the tank. 


In many ways toilets are genius in their simplicity. That said, looking into the tank at the different mechanisms can be intimidating. Lifting that back lid shouldn’t scare you off. With some basic knowledge of how the tank works, you will be well on your way to troubleshooting your Midlothian plumbing problem. Just remember that when in doubt, reach out to your local plumbing experts all your plumbing needs.

All About Toilet Tanks

The inner workings of your toilet tank are all interconnected, with one impacting the next in sequence. Keeping this in mind will help you get to the root cause of your issue.


There are two essential processes that your tank goes through whenever you flush the toilet can help narrow down any plumbing related issues. 


  1. The flush
  2. Refilling the tank. 


Let’s dive in. No pun intended.

Emptying or Flushing the Tank

The first function of your toilet is the flush. There are a few parts that are involved in this process.


Even if you have never looked under the lid of the tank, you will at least be familiar with this first part. The handle acts as a lever that starts a chain reaction to send pressurized water from the tank to the bowl, flushing waste down the main line.

Handle Arm

Attached to handle, running through the wall of the tank is the handle arm. When the handle is pushed down, the handle arm should go up. Handle arms can wear down over time as they are typically made of thin plastic and are put under stress each time the toilet is flushed.


The chain is exactly that: a chain that is attached at the top to the handle arm and at the bottom to the flapper. Have you ever pressed the handle and it feels like there is no pressure when you push it down? Chances are, there is an issue with the chain. Chains can come loose or break altogether, making them one of the more common plumbing issues that homeowners will encounter.

Flush Valve Seal

The flush valve seal, or “flapper” (as it is more commonly known) is attached to the bottom of the chain. This rubber piece creates a watertight seal that prevents water from dropping down into the bowl. If you notice water continually runs into the bowl, even minutes after you flush, your issue might involve the flapper.

Flush Valve

The flush valve is connected to the flapper and the drain opening that connects to the toilet bowl. This mechanism helps hold the flapper open so that the water can drain from the tank and flush the bowl. Without the valve, the flapper cannot remain open. 

Drain Opening

The drain opening is the connection between your tank and toilet bowl.


When these 6 components work in unison the flapper will rise and water will drop into the drain opening, becoming pressurized, allowing the bowl to be successfully flushed. The flapper will remain open until most, if not all, of the water has emptied from the tank. At this point it will fall back into place and seal so that fresh water can be brought in to refill the tank.


For plumbing issues that center on not being able to flush the toilet, you can be confident that something has gone wrong with one of these 6 components. Start at the top and work your way down until you find where the issue is. If all else fails, reach out to your local licensed Midlothian plumbing experts so that they can troubleshoot and get your toilet back in working order.

Refilling the Tank

Once your tank has successfully flushed, it’s next action is to refill so that it will be ready to flush when called back into duty. Just as the flushing components all worked together, the refilling mechanisms create a chain reaction to bring water back into the tank.

Fill Valve

Your toilet has a water line that is connected in the back of the tank. That water line is connected to the fill valve. When activated, it will allow fresh water to flow until the tank is full. If you hear water constantly running in the tank, your fill valve is a great place to start problem solving. 

Refill Tube

When flushing, you will notice that the tank is not the only thing that will fill back up. The toilet bowl will also refill with water. As water passes through the fill valve, the refill tube will help syphon water to the overflow tube on the flush valve. While not a common issue, start with the refill tube if you notice that your bowl fails to fill back up once flushed.

Filler Float or Float Ball

Depending on the age of your toilet, you may have an internal float that operates within the fill valve, or you may have an external ball attached to the top of the fill valve with a long stem. The float regulates how much water is in the tank and prevents it from overflowing. Once the float gets to a certain height the fill valve will disengage and the water will stop running.

Overflow Tube

The overflow tube acts as a fail safe in the event the float becomes stuck, breaks loose or if the filler valve malfunctions. Rather than let the tank continue filling until it overflows, excess water will move through the overflow tube into the bowl of the toilet.


When working properly, your toilet should refill in about three minutes. If water continues to run, you will have a good starting place to troubleshoot. More often than not, if this is the case, the filler valve is to blame.


When it comes to the mechanics of the toilet tank, taking a methodical look at the different parts and how they interact with one another will go a long way to getting your commode fixed and your daily life back on track. If you continue to encounter issues your next move should be to enlist the help of a licensed plumber. 

Finding a Plumber – Midlothian, TX

Understanding how the parts of your toilet tank work—and work together—is a great first step to troubleshooting issues as they arise. Having a trusted team to back you up for all your plumbing needs, whether maintenance or emergency, is the next.


Homeowners trust Dial One Johnson for all of their Midlothian plumbing needs. Our team has served the residents of Ellis County and the greater Dallas-Ft Worth Metroplex for over 50 years. With offices in Midlothian and Cedar Hill, and 24-hour service options, you can count on our team of professional, licensed plumbers to get the job done right the first time. Contact us today to learn more about our services and schedule an appointment.

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