What happens to the "stuff" falling down in a vertical pipe in a skyscraper? The answer:
The problem with wastewater running downhill and picking up a lot of momentum isn't as severe as it might seem. For one thing, flowing water tends to adhere to a surface, such as the inside of a pipe, and the friction slows things down considerably. There's also the phenomenon known as "terminal velocity," which skydivers are familiar with: after you fall through the air awhile, you reach a maximum speed. For water inside a pipe, this usually comes out to around 10 to 20 feet per second, depending on the diameter of the pipe and such.I love "and such".