How Toilets Work

Putting It All Together

Now that you have seen all the parts, you can understand the complete mechanism:

Pushing on the handle pulls the chain, which releases the flush valve.
About 2 gallons (7.6 L) of water rush from the tank into the bowl in about three seconds. The flush valve then reseats.
This rush of water activates the siphon in the bowl. The siphon sucks everything in the bowl down the drain.
Meanwhile, when the level of the water in the tank falls, so does the float. The falling float turns on the refill valve.
Water flowing through the refill valve refills the tank as well as the bowl. As the tank refills, the float rises, and when it reaches a certain level the refill valve shuts off.
Should something go wrong and cause the refill valve to keep running, the overflow tube prevents a flood.

What happens after it flushes? Read How Sewer Systems and Septic Tanks Work for a complete rundown.