And as gross as it sounds, this water is tested and generally clean and safe to drink. Like, cities downstream from water treatment plants do end up using this water for their own drinking supply.

But for our purposes, we’ll focus on the wastewater treatment process. How Do Wastewater Treatment Plants Work? Getty Images Advertisement - Continue Reading Below ...

Off-limits to the public for security reasons, we went inside the City of Milwaukee's Linnwood Water Treatment Facility to look at its history, its architecture and how it works.