Explainer No. 2
Press a handle and more than a gallon of water is gone in a few seconds, with no pump and no motor. A float, a rubber flap and a siphon do all the work. Step through it below, or flush it yourself.
Point at a part to find it in the drawing.
Pushing the handle down swings the lever arm inside the tank up.
Connects the lever to the flapper. It needs a little slack, or the flapper can't seal.
The rubber plug over the drain hole in the bottom of the tank. Once lifted, it floats open until the tank is nearly empty.
Rides the water level, and tells the fill valve when to open and when to stop.
Lets supply water in while the float is low.
Not a part, but it does the real work: it falls, it seals the drain, and it pulls itself out of the bowl.
Stores the next flush, held above the bowl so gravity can do the pushing.
If the fill valve ever fails to shut off, water spills down this tube into the bowl, so the tank can't overflow.
Sends part of the refill water down the overflow tube, to top the bowl back up.
Tank water enters the bowl through holes under the hollow rim. Some toilets also have a jet near the bottom, aimed into the trapway.
The curved channel cast into the porcelain. The top of its hump, the weir, sets how high the bowl water stands.
On the wall behind the toilet. Close it and the tank can't refill.
Add water slowly and the bowl level barely moves: the extra just spills over the weir. A flush works only because water arrives fast enough to fill the whole trapway. Then the water falling down the far side pulls the rest after it.
A lifted flapper floats. It stays open on its own while the tank drains, then settles back onto its seat as the water drops. You only have to start the flush; the flapper finishes it.
The overflow tube is a safety drain. If the fill valve doesn't shut off, the extra water runs down the tube into the bowl and out the drain, instead of overflowing the tank. It's also where the refill tube sends water for the bowl.
A worn flapper lets tank water seep into the bowl. The float slowly drops until the fill valve runs for a few seconds, with nobody nearby. To check, put a few drops of food coloring in the tank and wait 10 minutes without flushing. Color in the bowl means the tank is leaking into it.
Sir John Harington described a flushing toilet in 1596. In 1775 Alexander Cumming patented a flush toilet with an S-shaped trap, the bend that holds standing water to keep sewer smells out.
More explainers