To start out you might be surprised at the end what water we are drinking. So when you flush the toilet, take a shower, run the sink, etc. It will go into a pipe called a branch pipe. When I say branch pipe I mean a normal sized (usually comes out of a main pipe) average pipe, like a branch out of a tree trunk. So, the water goes through the branch pipe into the Chicago river if were talking about Chicago, or the main river or stream of your state. After, the water will go into whats called an outlet which brings it into a stabilization point or pond, that point filters all the toilet water. Then after it filters it goes into the main sewer line. So there are sections from section A to E (they each cover about 5 to 7 thousand miles) and there can be about 5 branch pipes coming off the main sewer line in each section, and on those brach pipes are more branch pipes. Those branch pipes lead into houses and the water goes into your shower or sink etc, and if it doesn't make it into any branch pipes it will go into the ocean. Also, did you know a sewer system in only Chicago is 35,000 miles. Also, we are kind of drinking toilet water but it is just filtered.