This is 99% invisible.

I'm Roman Mars.

Every time you go to the bathroom, you should thank Alexander Cummings.

We actually featured a whole story about him because Alexander Cummings was the first

person to patent a flushable toilet.

He didn't invent the flush toilet, but he did connect it to an S-shaped pipe, which

uses water to stop sewer gas from coming up and stinking up your home.

And before Alexander Cummings, that used to happen a lot.

Whatever was underneath the toilet could come back up.

People didn't like bad smells, but they also thought that bad smells carried disease.

That's how the flush came about.

That's Chelsea Wald.

I'm the author of Piped Dreams, the urgent global quest to transform the toilet.

The flush toilet took a while to catch on, but once it did, it became part of a system

we still use today.

Which Chelsea calls the gold standard.

Here's how it works.

Your poop once deposited into the toilet and you flush it down, goes into a sewer system

that runs under the city.

And there it combines with water and with everyone else's poop and anything anyone puts

into their sinks and their toilets and their showers and their washing machines and their

dishwashers.

...