Have you ever spent much time thinking about how a toilet works? After all, it’s one of the inventions of the modern age that has really changed our comfort and quality of life — imagine if every household still had to maintain an outhouse instead of having a toilet with running water in their bathroom. But unlike some appliances you have in your house and understand how they work, the toilet might seem like a total mystery.
Why should you understand how the toilet works?
It’s a good question. However, if you understand how the toilet works, you can easily diagnose, avoid, or solve most problems involving a toilet’s operation, so you don’t have to call in a plumber to fix something you could easily take care of yourself with a few tools you probably already have around the house or parts you can pick up from the hardware store.
Let’s start by discussing the different parts of the toilet:
The handle: You know this part of the toilet — it’s what you push down to make the toilet flush.
The tank: This is the container on the back of the toilet that holds water until it is deposited into the bowl.
The bowl: What you might think of as the main part of the toilet. Water goes from the tank into the bowl, and from the bowl, everything is flushed away into the pipes.
The fill valve: This is the valve that draws water from your plumbing and into the toilet tank.
Flush valve: This is the valve that opens up to move the water from your toilet tank into the bowl.
Float: Also known as the buoy, this is the large hollow ball connected to your fill valve. It’s how your toilet knows there’s enough water inside the tank.
Overflow tube: This catches any excess water that might overflow from the toilet tank.
Flapper: This is the rubber stopper that closes the opening from the fill valve into the toilet tank.
How does it all work?
Once you have a basic understanding of all the different parts of the toilet, it’s easier to understand how they all operate in conjunction to move water from the tank to the bowl and finally out through your pipes. Here’s a basic rundown:
Most of the time you approach a toilet (a properly functioning one, at least), you can expect to find water in the bowl and in the toilet tank. When you flush the toilet, you push down on the handle, and the handle is connected to a rod inside the toilet bowl that lifts up the flapper.
When the flapper comes up, it allows all of the water that is inside the toilet tank to go rushing through the flush valve into the bowl.
At this point, two things are happening simultaneously — water is leaving the bowl and entering the tank. Inside the bowl, the rush of incoming water pushes the water that’s already in the bowl into what’s known as the trapway, the curve of piping just below the bowl that leads to the pipes exiting your home and leading to the sewer. When enough water goes into the trapway, it is suctioned into your pipes and replaced by air, which creates a suction that stops the water in the bowl from draining.
While this is happening, your fill valve starts to put water back into the tank.
By this point, you’ve released the handle on the toilet, and the flapper has fallen back into place, sealing off the exit to the flush valve so that the tank can refill.
Water from the refill valve continues to fill the tank. As the water level rises, the float goes up. When the water level reaches a certain point, the positioning of the float will close the refill valve off so that no more water comes in. If there’s any excess water for any reason, it will go into the overflow tube and drain out of the tank. Sometimes it will take a few seconds for your refill valve to put enough water in your tank for another flush, which is why you have to wait a little while between flushes.
What can I do with this information?
The next time you have a problem with your toilet, your understanding of how the toilet works will help you diagnose the problem. Is your toilet constantly running? There might be a problem with the float, and it’s not turning off the refill valve. Or your flapper could be forming an improper seal, which causes water to constantly leak into your bowl. Lift the lid of your tank and watch what’s happening so you can determine what needs to be fixed.