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How Does a Toilet Work?


How a Toilet Works

The toilet has gone by at least 101 names in its relatively short lifespan. Short because the modern toilet as we know it has only been around for about 100 years. Everyone is familiar with what a toilet is, what it’s used for, how to use it, and all that. I would imagine that about half the people out there have even opened the back of the tank out and fiddled around inside on at least one occasion. But do you know how a toilet works?


The Bowl Siphon

A toilet, in essence is a simple machine, and is made up of 3 main sections, each with a couple of key parts. The first section we will talk about is the Bowl Siphon. The bowl siphon portion of the toilet is the part that you sit on. It’s made by mold, and almost all toilets are made out of porcelain. The bowl siphon works based on the laws of gravity and weight. There are no moving parts in the bowl siphon, and is used as the exit part of the toilet. Water is brought into the toilet from the flush mechanism (next section), and used to evacuate the bowl. Water is dumped into the bowl and causes the contents of the bowl to be flushed in an “S”, “U”, “J”, or “P” shape, upwards, then back down the outlet pipe. The shape of the tube and the way its designed helps in how it works, but also has an added bonus, the water being in the tank acts as a natural smell blocker, keeping the smell of the sewer out of your toilet. One of the interesting things about this portion of the toilet is that the water always stays the same. This is because of the siphon tube. When small amounts of water are placed in the bowl, it is able to even itself out. But when large amounts, like the amount the tank can hold, it fills the siphon tube quickly, causing the bowl and pipes to be pressurized and a vacuum is formed and the contents get sucked out of the bowl. Once the bowl is empty, the siphon looses its vacuum on the toilet and pipe and the process automatically stops.


The Flushing Mechanism

The Flush Mechanism is more or less the tank of the toilet. The tank of the toilet is the only other porcelain part of the modern toilet, and is usually made either as a whole unit or as 2 separate halves that are later joined for a watertight seal. The flush mechanism is responsible for getting water to the bowl fast enough to activate the siphoning effect of the toilet so that the toilet will work. The tank on the toilet usually takes about 30-60 seconds to fill, and about 3 seconds to flush. When you flush the toilet, the flush valve opens , dumping the contents of the tank down a 2-3 inch drain hole. This hole lets water into the bowl, through a large hole called the siphon jet, while the rest is put through the rim of the tank and flows out through small holes down the sides of the bowl. The siphon jet releases into the siphon part of the toilet, and it is this that makes the toilet suck the bowls contents out and down the drain.


The Refill Mechanism

This is the part that most people are at least familiar with. The flush mechanism is one of the more complicated (but still actually pretty simple) components that make a toilet work. Simply put, the flush mechanism activates the rush of water needed to start the toilet. Flushing the toilet sends the water stored in the tank to the siphon and causes the siphon to work, causing the contents of the toilet to be flushed. It all starts with the handle. The handle, accessible on the outside of the toilet, is attached to a chain, which is attached to a rubber flap, covering the main toilet drain plug. Pressing the handle causes the flush valve to rise. The drop in water in the tank causes the filler float to drop, causing the filler valve to open, which starts water flow inside the tank. Most of this water is used to fill the tank, with some of the water going down the overflow tube into the bowl refill ports and refills the bowl, priming the system for the next flush. As the water level in the tank rises, the float will also rise. Once the float reaches a pre-determined height, it automatically turns off the water. The overflow tube, keeps the toilet from overflowing and flooding the bathroom. For a properly working toilet, the float should be set so that the water automatically turns off before the overflow tube, but with enough to properly and effectively flush the toilet.


So in other Words...

Pushing the handle causes the flush valve to rise, causing the contents of your toilets tank to be dumped into the siphon jet in about 3 seconds, causing your toilet to create a vacuum and suck the contents of the toilet bowl out. Meanwhile, the refill mechanism is hard at work, putting more water into the tank, and preparing for the next flush. Once the float has reached its designated stop setting, the toilet stops filling and the process is completed. All without electricity, hydraulics, or mechanical parts. The toilet, is indeed a very simple, yet complicated, machine.Because of that, working on a toilet and toilet repair as well as plumbing repair can be a very challenging and skilled labor.But what happens with what goes down the toilet? Read How Does a Sewer and Septic System Work? for the answer to that.

1.6 liter Toilets Could become thing of the past.

If you have an issue with your toilet you may want to consider repairing it instead or replacing it because 1.6 liter flush toilets are under scrutiny for the amount of water they use. Federal guidelines are targeting ways to increase conservation and by reducing the amount of water a toilet uses has a big impact. If you like the 1.6 liter flush just have your current one repaired.

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SixIRISHKids from USA on July 08, 2014:

Great Hub. Often a confused mind about how the toilet actually works. Thanks for sharing!

Kenneth Moody (author) from Destin, Florida on January 29, 2013:


iguidenetwork from Austin, TX on January 28, 2013:

Toilets are the one we use everyday, but we don't bother to know what's in it and how it really works. Thanks for putting this all out. Great work. Up, useful, interesting. :)

Kenneth Moody (author) from Destin, Florida on January 26, 2013:


Randy McLaughlin from Liberia, Costa Rica on January 25, 2013:

I never have thought to write anything about toilets. Good job.

Kenneth Moody (author) from Destin, Florida on January 25, 2013:

No problem, glad I was able to help out!

Loveofnight Anderson from Baltimore, Maryland on January 25, 2013:

This was indeed a good read, I did not know what to expect when I first started reading, but I also knew that I did not have the answer to the question. How does a toilet work ?, it seems fairly simple on the surface but it deals with more than pouring water down a hole. Now when my grandson ask me how or why it works like that I will look him straight in the eye and give him your answer.I'm really going to look smart now.....thanks for the info.

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