UNITED KINGDOM — One of the more overlooked marvels of the modern skyscraper is its plumbing system, which handles the very important job of managing the building’s waste.

British drainage expert Mark Briggs, while speaking to the Daily Mirror, explained how waste flushed from a height goes down at speeds of up to 122 mph as it hits terminal velocity.

The bottom of the pipe levels out to slow down the flow and minimize any bounce backs.

Buildings 20 or more storeys high also need to have separate stacks or pipes for toilets in the first two floors, to prevent anything from spewing out.

The design of a toilet system depends largely on the number of appliances, and the amount of fluids those appliances are expected to discharge.

Since skyscrapers produce more fluid discharge, its drain pipes need to be much wider than those in single family homes.

Pipes are typically made from PVC, but some buildings use cast iron for extra protection against rats, fires, and the sheer pressure of tons of human waste rushing through them.