• Joseph DeLorme

How the Toilet Works

Updated: Jan 11


Thankfully the days of sitting in a smelly outhouse are in the past and the time of indoor plumbing is going strong. Using the toilet is something that is learned at a very young age and is just accepted as a part of something that must be done. The toilet is a marvelous invention and no house is livable without one. No thought might be given to how a toilet works until that handle is pressed and nothing happens. How does a toilet work?


Parts of the Toilet


The toilet is attached to a supply tubing that connects to the main water supply of the house. This is what fills the tank that’s usually on the back of the toilet unless it’s a tankless toilet. When you lift the lid to the tank you should see a chain that runs from the handle all the way down to the bottom of the tank and attaches to a flap called a flush valve and the whole system is known as the flush mechanism. On the other side will be a column with a ball float, this is the refill mechanism.


The bowl of the toilet is something that everyone is familiar with. It’s what catches the waste. On top of the bowl is the seat that can be lifted to reveal the rim of the bowl. Just inside the rim there are little holes all the way around that allow water to run into the bowl. At the bottom of the bowl towards the back is the hole that everything goes down. Just through that hole is an unseen part of the toilet that is highly essential. It’s called the bowl siphon and it is the reason the water is sucked out in the way that it is. It’s a U shape or a snake shape before it gets to the plumbing pipe.


What Happens When You Flush?


When the lever is pressed it lifts the chain on the inside of the tank and raises the flap from the drain hole. When this happens the roughly 2 gallons of water inside the tank is released and quickly rushes to the bowl. As the water rushes out, the ball float on the refill mechanism drops with the water level. When it gets to a certain point it flips a valve on the refill mechanism that turns the water on. The water is released simultaneously through those little holes around the rim and through an overflow tube.


Imagine that the tank is a bucket of water that is being poured into the bowl, this is where the magic happens. If the bucket was only filled with 6 liters of water or less and dumped into the bowl, the water level would never change. This is where that U-shaped siphon comes into play. It ensures that if too much water is poured in it spills over and goes down the drain while maintaining a full bowl. When you pour the 2 gallons of water in it makes the toilet flush and empty completely. When the bowl is flooded fast and with a lot of water the siphon is flooded, and no air remains. This causes an automatic response that sucks all the water from the bowl and creates that signature flushing sound. When the air returns to the siphon it stops siphoning and starts filling.


When all the water drains out of the tank, the flap rests back down and covers the drain hole the tank is ready to be refilled. If the flap doesn’t rest back down, the tank will not fill. The water runs from the water line and through the refill tube to fill the tank up. That floating ball that flipped the valve to turn the water on will start rising as the tank fills and eventually reach that valve again and turn the water off. When the lever is pushed, the whole process repeats.


Most of the common toilet problems that a person runs into are easily fixed without a professional. Usually, they are related to the flush valve or the ball float. Adjusting or replacing one or the other will generally fix problems associated with dirty water in the tank or the toilet not flushing all the way. Often, the chain that connects the handle to the flap is too long or too short and will not lift it up or allow it to settle. Adjusting the length of the chain is an easy fix.


Now the inner workings of a toilet are no mystery and while sitting for nearly 3 hours a week on the porcelain throne there is a peace of mind knowing that everything will go down the way it should. Also, 3 hours a week adds up to approximately 156 hours a year, which means that the average person spends 6 ½ days out of the year on the toilet.

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