How Does a Toilet Actually Work?

Ah, yes. The toilet. Miracle of modern hygiene. Ever-present comfort. Loo. Lavatory. WC. Toilets have been around for thousands of years in one capacity or another. The commode as we know it today, however, wasn’t commonplace until after the turn of the 20th century. Now, every home you enter has at least one.

Because toilets are so common, it’s easy to forget how impressive their water-handling engineering actually is. Unless you’re us, that is. That’s why we’ve detailed the entire process from start to finish for you below.

The Parts

First things first, we need to list all the parts that make a toilet work. A toilet’s main function relies on three elements: the bowl siphon, the flushing mechanism, and the refill mechanism.

The Bowl Siphon

The Bowl Siphon is made up of the rim, the bowl, and the siphon. This part of the toilet has no moving parts. Toilet rims are usually made from a type of plastic, and the bowl itself is usually porcelain.

The Flushing Mechanism

The flushing mechanism is inside your toilet’s tank. There’s a handle attached to a chain inside the tank. When you push the handle to flush, you’re actually pulling the chain. Pulling the chain lifts the flush valve it’s connected to. This opens up a drain hole in the bottom of the tank that allows water to quickly enter the toilet bowl.

The rapid introduction of water from the tank creates suction in the bowl in the form of the flush. That suction pulls out whatever’s inside the bowl down into your pipes.

The Refill Mechanism

The refill mechanism is a valve that’s responsible for turning water on and off. This mechanism senses where a device called a float sits inside the tank. The float, well, floats in the tank’s water. When the water’s low, the float is low. The refill mechanism senses that the float is low and opens, adding water to the tank. As water enters the tank, the float rises along with it.

When the float reaches a certain point, the refill mechanism closes again. The refill mechanism also includes an overflow tube, which dumps excess water into the bowl should the float malfunction.

How it Works

While describing the individual parts of a toilet, we’ve given you a basic idea of how a toilet does its job. Let’s bring it all together here with a step-by-step walkthrough of flushing the toilet.

1. You go to the bathroom. When you’re done, you push on the handle, which pulls the chain.
2. Pulling the chain releases the flush valve. The flush valve releases approximately 1.5 to 3 gallons of water from the tank into the bowl.
3. The flush valve reseals itself so the water can’t re-enter the tank.
4. The speed of the water rushing into the bowl creates a siphoning effect. That siphon sucks everything in the bowl down into the drain.
5. As water leaves the toilet tank, the water level falls and the float sinks with it.
6. When the float sinks, it activates the refill valve. The refill valve opens and water re-enters both the toilet tank and the bowl.
7. When the float rises back up to a certain level, the refill valve closes again.
8. If the float malfunctions and the refill valve doesn’t close, the overflow tube redirects the water to prevent flooding.

Cool, huh? Toilets are amazing because they are both simple and complex. Their engineering has been refined over the decades to give you a simple solution to a biological need. Taking good care of your toilet will make sure it’s always working as intended.

Invest in regular drain cleanings and your toilet will never do anything other than exactly what was described here. For everything else, there’s Ben Franklin Plumbing.