Book 1, Question 114 · Video
How Does a Toilet Flush? The Science of the Siphon!
Ever wondered what happens after you flush? When you lift the flap, water rushes from the tank into the bowl. The fast water carries waste away, and then a siphon pull finishes the
Read the full answer →What Crafty Clover says in this video
Intro
Hi! I'm Crafty Clover! Let's discover something amazing. How does a toilet flush?
The Big Idea
A flush is a clever water trick. The tank on the back stores water. When you flush, gravity and a siphon team up to whisk everything away. And it doesn't need any electricity at all!
Lift a Flap
Step one: you lift a flap, and water rushes! When you press the handle, a chain lifts a rubber flap, called a flapper, at the bottom of the tank. Gravity pulls all that stored water down into the bowl, super fast!
Fast Water
Step two: fast water carries waste away. The rushing water swirls into the bowl and fills it up quickly. The water spills over a bend in a curvy pipe hidden inside the toilet, called the trapway.
Siphon Pull
Step three: a siphon pull finishes the whoosh! When the curvy pipe fills with water, it becomes a siphon, like a giant straw. The water rushing down pulls everything in the bowl along, until air sneaks in with a gurgle. Then the flap drops shut, and the tank refills.
A Closer Look
Let's look inside the toilet! The tank stores water for the next flush. A floating ball rises as the water refills, And when it's high enough, it tells the fill valve to shut off the water. The curvy trapway keeps a little water in the bowl, to block smelly sewer air.
Quick Facts
Quick facts! The tank stores the water for the next flush. Newer toilets use about six litres of water or less for each flush. The water left in the bowl blocks stinky sewer smells. Flush toilets are old! One was built for a queen in fifteen ninety-six.
Think Like a Scientist
Now, think like a scientist! Flush the toilet, and stay to listen closely. First comes the big whoosh, then a gurgle when air sneaks in. Next you'll hear a hiss as the tank refills. Count how many seconds it takes! Ask a grown-up to lift the tank lid, so you can watch the float rise.
Outro
Every flush is gravity and a siphon working together, with a tank that's always ready for next time! Crafty Clover can be found on Amazon Books, Google Bookstore, and Apple Books. Available for purchase or download! Bye for now!