The sewer is a system of underground pipes and tunnels that transport industrial wastewater from the city to the sewage treatment facility just beyond the main river. Vertical pipes, or otherwise known as manholes, connect the main pipes and tunnels to the surface of the city. The sewers are generally powered by gravity, through there are pumps stationed here and there to help the flow of sewage if necessary. Larger “outfall” pipes allow wastewater to pour into parts of the river where the sewers become flooded by water entering the city’s storm drains. These pipes do not overflow unless there is an excessive downpour of rain, so they are commonly used as a temporary residence for the homeless and even stray animals. The sewer tunnels are home to rats and other rodents.
