- [Narrator] This is the toilet.
This is also a toilet. So is this.
And this is the crumbling infrastructure underneath.
- In the US and other places,
the wastewater infrastructure is aging
and it's not very well suited
for dealing with a lot of the challenges in the future.
- [Narrator] This is Chelsea Wald.
She spent over eight years researching the toilet
and discovered it needs a big upgrade.
[toilet flushes]
- [Chelsea] Why hasn't the toilet really changed?
One of the reasons is technological lock-in.
Our predecessors spent lots of money putting these pipes
in the ground and then we're also
kind of psychologically locked into it.
It's hard for us to imagine something different.
- [Narrator] Technologists are redesigning the toilet
to do more than what we asked of it before.
- Previous societies knew that pee and poo
were valuable resources in terms of the nutrients in them.
The current sewage system makes it difficult
to recover that but it would be a lot easier
if we could do it at the toilet level,
rather than waiting for all the mixing to happen
and then trying to get it all out at the end.
One thing that I've seen here in the Netherlands,
piloting of vacuum toilets, these use very little water
and they suck out the waste and keep it separate
from other household wastewater,
the gray water coming out of the house
and that makes it possible to make better use of that waste.
Another innovation that I've seen
that's promising is urine diversion toilets.
So toilets that actually separate pee and poo.
These have been very hard to develop, to design
because they are awkward to use.
There is a new design called the urine trap
that does this separation a little more seamlessly
with less trouble to the user.
So the high tech toilet of the future might be a toilet
that has medical capabilities.
I talked to one innovator who has made a toilet
that actually images your poo.
And from that can determine some things about your health
and especially over time and to alert you
if there might be a problem.
The first big comprehensive sewer system
for removing human waste from a city was in London,
in the 19th century.
But some of those original sewers around the world
from the 19th, early 20th century
are still in the ground and still operating.
One big problem from some of those old sewers,
it's they were combined sewers.
So they combined stormwater with all this household water.
When there's a storm, even if it rains a little bit
in some places, the sewers overflow.
There's a couple of ways that cities are dealing with this.
It's a very, very difficult problem.
Some are digging big tunnels.
It's very expensive, massive storage underground.
Some are building green infrastructure above ground
to absorb a lot of that stormwater
so it doesn't even go into the sewer.
And then some cities are making their sewers smarter.
South Bend, Indiana have a combined sewer
that they've started putting these, you know,
movable devices, remote devices into their sewers.
And they've been able to reduce the number of overflows
a lot without actually having to dig any extra tunnels.
- [Narrator] While some cities are making sewers smarter
other cities are reimagining the sewer as an energy source.
In Vancouver, a sustainable energy system was used
to heat the city's Olympic village.
- [Chelsea] You can also start to harvest stuff from sewers.
Kind of works like the reverse of a refrigerator,
uses a fluid to capture the heat and then that heat
can then be transferred into a distribution system
to run through the building,
just like any other heating system.
From the perspective of someone in the building,
they would never know that the source
of the heat was sewage.
Many cities already have a big mix
of sanitation technologies.
That diversity can actually make cities
more resilient in a way.
So if you can say, as a city grows,
instead of expanding the sewer system,
it might make sense instead to introduce
building scale systems or district scale systems
or if there are areas where it really makes sense
to have onsite sanitation, because it's kind of more rural,
you could introduce systems there that make sense,
you know, ecologically for that area.
- [Narrator] Wastewater treatment plants take everything
we dumped down the drain and toilet, filters it
and uses microorganisms to clean the water.
- One of the problems that wastewater treatment plants face
is the residual sludge that comes out of this process.
But there's people who are now looking for new ways
to make use of this sludge.
One is to take that sludge and turn it
into a kind of biocrude that can then be used
as a transportation fuel.
In a lot of places, people have been inadvertently
drinking recycled re-used wastewater for a long time.
So these programs are called
indirect potable reuse programs.
Orange county was the pioneer of this program.
They actually clean their water to drinking water standards
using advanced technology
and then they inject it into an aquifer.
And then on the other hand, you have direct potable reuse,
and that would mean taking the cleaned up effluent
and putting it back into the pipeline
directly as drinking water.
There is a fear of the yuck factor or the ick factor,
which has held back these programs in the past.
There is a big trend for pilot projects,
for direct potable reuse all over the world
but especially in the United States.
Even in the last year or two,
it's just going to be one of the most reliable sources
of water that's available.
And you'd rather have direct potable reuse water
than no water coming from your tap, that's for sure.
So in writing this book, I came across just a wide variety
of people working on all different aspects of the toilet
from the design of public toilets
to the design of the toilet bowl
to improving sewer systems to improving pit latrines
to improving wastewater treatment
to using the products of wastewater treatment.
The toilet is really one of the most fundamental
technologies that underpin human society.
And if you want to think about it poetically,
we are connected to each other as humans
and to the planet through the toilet.
So it is so important that our toilets are good,
that they're healthy, that they're sustainable
and that everybody has access to one.