how toilets work
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Before we begin our discussion of how the bowl system works, let's open up our trusty diagram in a separate window by clicking here.

The bowl system is really only made of two parts, the bowl and the siphon. Despite its simple looks, the siphon is really the main part of what makes the toilet work! Notice that the water level in the tube of the siphon is the same as the level in the bowl. If you were to add a small amount of water to the bowl, say one cup of water, the level would rise equally in the bowl and the siphon, and any water that was higher than the edge of the siphon would simply spill over and is drained away. Now, let's say you added a considerably larger amount of water, say two gallons, directly to the bowl all at once. In this case, the siphon would become completely filled with water for a split second - just long enough to cause the siphon to forcefully suck all of the water out of the toilet bowl, and drain it away. Now, it would obviously be quite inconvenient to keep a bucket full of water next to the toilet everytime you wanted to flush, so let's investigate how we can fill the bowl with enough water to cause the siphon to drain.
Continue on to flushing the toilet.