system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 How do toilets flush without overflowing on water and still have water left over in the bowl?
gpt
The pipe from the bowl to the sewer forms a bend that traps air/gases behind the water in the bowl. When you flush, the water in the bowl rises above the bend in the pipe and pressure moves the water into and around the bend. The water is now falling down the pipe, creating a vacuum behind it, pulling water from the bowl into the pipe. Once air reaches the bend in the pipe again, the falling water will now pull air into the pipe instead of the water in the bowl, leaving enough as it refills from the tank to trap another pocket of air in the bend, ready for your next flush.