This episode of SciShow is brought to you in partnership with Gates Notes.
You can learn more about the latest innovations making toilets and sanitation safer,
more affordable, and more resource-efficient at gatesnotes.com.
This year, they’re reflecting on progress made over the last decade for the tenth
anniversary of the “Reinvent the Toilet Challenge.”
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There are a lot of circumstances where we wish we had a clean slate.
That we could push a button and wash all of our worries away.
Today, in much of the world, that dream is a reality…
at least so far as poop is concerned.
Flush the toilet and we no longer need to worry about the bacteria and gases in
sewage or the illness that we might acquire from coming into contact with our own
waste, which can be a serious problem.
The World Health Organization estimates that diarrheal diseases kill
millions of people every year, and intestinal parasites
run rampant in areas without sufficient sanitation.
But across the world, and throughout history, different peoples have developed
different ways to deal with their own waste.
And while they didn’t always nail the design,
their efforts to keep themselves safe have led to the toilets
and sanitation systems we know and love today.
So let’s take a look at some thrones from history that show us how far we have
come, and how we can still improve the health and safety of our bathroom visits.
The Mesopotamians have been credited as inventors of the first toilet
and may have been the earliest people to have dedicated bathrooms,
dating to the fourth millenium BCE.
These involved pipes measuring 1 meter wide, and 4.5 meters deep,
that drained to cesspits.
Archaeologists have also found toilets with brick seats and pipe
with a water-repellant lining made of bitumen.
Bitumen is derived from crude oil, and today we use it in paving roads.
But the Mesopotamians were interested in other applications.
It is both slippery and hydrophobic, meaning it repels water.
So waste wouldn’t stick on its way down the tube.
It seems like not everyone trusted or had access to
this newfangled technology, though.
Only around one fifth of Mesopotamian households had toilets installed!
However, they also understood the importance of keeping poop far away
from their living spaces.
If the poop is far away, either you or the poop would have to travel to come back
into contact and make you sick.
Pathogens like viruses, salmonella, cholera, tapeworms, and more can survive
and reproduce for days, months, or even years under ideal conditions.
And they can travel from poop to water, food,
inanimate objects, people, or other animals.
So, yeah, that’s where we get sewage pipes.
You don’t just make a big pit for your waste; you get it the heck out of there.
Mesopotamian settlements Chogha Mish in present-day Iran,
Tell Asmar in present-day Iraq, and Ugarit in present-day Syria
show evidence of sewage pipes used to transport waste outside city walls.
Bitumen coating could only do so much to keep sludge
moving away from everyone’s living spaces.
By around 1700 BCE, two civilizations from different parts
of the world had introduced a tool that more effectively moved it downstream.
These were the Minoans, from present-day Greece,
and the Indus Valley civilization of present-day India and Pakistan.
Independently of one another, they each created the flush.
Instead of sitting over a dry tube, these smart stinkers sat
over a tunnel with water flowing through it.
While both civilizations had flushing technology and wooden toilet seats,
they differed in where they got the water supply from.
Evidence from the Minoan capital city of Knossos, in present-day Crete,
suggests that the Minoans took water from their roofs to flush their toilets.
While the Indus Valley people of Harappa, Mohenjo-Daro, and
Lothal funneled water from nearby wells into their sewage system.
Either way, in both the Minoan and Indus Valley civilizations,
water would get poured down the latrine to wash away their filth.
And then, the waste would stream down into an
underground sewer system to take it away.
The toilet at the royal palace in Knossos allowed for water to be poured into a
separate hole that mixed with the sewage under the seat.
They even had a hole outside the bathroom door so that
someone else could flush for you!
Which seems like an unnecessary amount of luxury, even today.
The flush was an innovation in moving waste away.
But not everyone throughout history nailed that concept.
In fact, some of the things the Romans thought would make them cleaner,
instead may have made them sick.
The Roman Empire of the first century BCE had both
private and public baths spread throughout cities.
But those in private homes were… a bit dangerous.
They figured that a waste system for their bodies could pull double duty as a
waste system for their food scraps and pretty much everything else.
So the private toilets were usually located very close to the kitchen,
where they cooked their food.
It’s likely that the Romans’ poor potty placement led to diseases like dysentery,
typhoid fever, and diarrhea, among others.
On top of that, and I literally mean on top of that, the
sewers could get blocked up pretty regularly.
So their waste would pile up until the sewers could be cleaned out.
That may have led to backflow of wastewater during floods,
and corresponding increases in pests and fecal-borne disease.
If that wasn’t enough, this pit of waste in the middle of their home
may have led to the accumulation of hazardous gases.
Microbes in waste can produce flammable gases like methane.
With nowhere for the waste and its fumes to go, archeologists have speculated that
from time to time, Roman bathrooms may have caught fire.
So although Romans adopted toilets widely, they may not have been entirely
effective in protecting them from disease… and other, more unique risks.
If only the Roman toilets had what the Mayans had: water pressure.
They could have used it to give that built-up waste an extra nudge down the sewer
and away from their kitchens.
Minoan sewers had a series of pipes that decreased in diameter,
which increased the water pressure.
But the Mayans took it to the next level.
Unlike many other Mayan cities, the city of Palenque circa 250 CE had access to
an abundant supply of water for most of the year.
But summer was a time of drought.
And if you can’t flush when the weather is dry, you’re not getting the benefits.
So residents constructed a limestone watershed under the city,
based on natural water flow patterns.
That was possible because the city was constructed
over top of existing stream beds.
Most Mayan cities had more flat ground to build on,
but in Palenque, they had to create flat ground for their city.
Mayan engineers constructed narrowing conduits to keep
the water under pressure.
And then, they covered the conduits to build on top of the now-open space.
This underground, pressurized chamber meant they had access
to water when above-ground streams dried up.
And that meant they had access to flowing water for sanitation all year-round!
By the 11th century CE, you might think that medieval European lords
in their castles would be living in luxury.
But when your main source of waste disposal is your moat, well, maybe not.
If you lived in a castle, you might have had literal poop chutes.
You feel that rumble in your tummy, head over to the tower toilet,
you let ‘er rip, and gravity does the rest.
Your poop would have simply fallen down a pipe thanks to gravity, and been
evacuated from the castle and into the moat or a river,
or it would just pile up in the tower.
Some of those towers were pretty tall, so just imagine the
amount of waste they could contain.
And this was the case in Chepstow Castle in Wales.
All of the waste that collected in and around castles could
attract visitors in the form of rodents, fleas, and lice.
That’s because even though feces is a waste product, it can still contain enough
nutrients for it to be worthwhile for animals to eat.
For example, our bodies excrete an excess amount of vitamin A via our poop.
So you’ve got rats coming along to eat the... “tasty” waste lying around.
And they can become a vector for disease.
Some parasites infect humans only after infecting an intermediate host,
also known as the rat in your chamber pot.
And these parasites would have been far worse than mild inconveniences.
Some researchers hypothesize that lice in medieval waste were
key transmitters for the Black Plague!
But folks in the Middle Ages apparently found a way to turn their filth to their advantage.
Microorganisms in feces consume oxygen, nitrogen,
and phosphorus from the waste.
These byproducts can react with each other to create ammonia.
And it is thought that resourceful Middle Agers would hang their clothing near their
waste chutes in the hopes that the vapors would kill those nasty fleas.
What’s more important: not having fleas or not smelling like literal poop?
Apparently not having fleas.
Ok, these days, we try to keep those disease-bearing critters
away from ourselves and our waste.
And there’s actually a specific technology that keeps unwelcome smells from
wafting up after you sit on the throne.
It’s the S bend, or S trap.
You may have noticed that many present-day toilets have
those curvy pipes either behind or inside them.
Patented in England in 1775, this extra bit of plumbing traps gases
in the pipes and keeps them out of your home.
The curved shape of the pipe keeps some water trapped in the lower cradle.
And that way, there’s a little reservoir of water between you and any
gases that might try to sneak up.
And that’s the power of the S bend.
There are also updated versions, the P bend and U bend,
which do a better job of keeping water in the cradle and trapping gases.
And in the 19th century, an English plumber named Thomas Crapper popularized
this technology with his own line of toilets.
So, yeah, you can go ahead and giggle about that.
It’s a pretty great name, and it is not an urban legend.
Crapper was a real guy.
But the S bend, P bend, and U bend use water to solve our problems again,
and we might be using too much of a good thing.
Introducing water to the waste removal system was a huge innovation.
The Minoans, the Indus Valley people, and the Mayans all hit on that.
But now we know that water conservation is important as well.
Some newer toilet designs, that are especially popular in arid places like Australia,
literally have a “number 1” and “number 2” setting, where you can determine
how much water your flush needs with the touch of a button.
So what is the future of the toilet?
We have an incredibly powerful ability to communicate
that we have never had before.
If the Mayans could have taught the Romans a thing or two about water pressure,
maybe we’d all have better toilets today.
And we know we still have more to learn.
Engineers are working on things like ways to reclaim drinkable water
and produce electricity, all from human waste.
Luckily, we get to build on of the progress made by all these different peoples.
Instead of piling waste on top of waste, like early toilets did, we can pile
innovations on top of innovations to move sanitation and health into the future.
If you find toilet history as fascinating as we do, you’ll probably enjoy reading
Gates Notes, the blog of Bill Gates.
In fact, the “Reinvent the Toilet Challenge” is celebrating a
decade of toilet innovations this year!
Humans have been finding new ways to get rid of their waste and improve
sanitation for quite a long time, but there’s still a long way to go.
The Reinvent the Toilet Challenge was created to inspire new technologies
that make safe and affordable sanitation more accessible for
communities all over the world.
You can learn more about how scientists have tackled this challenge and found
ways to reinvent the toilet at gatesnotes.com.
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