All language subtitles for Ancient.Engineering.S01E07.The.Power.Of.Water.1080p.AMZN.WEB-DL.DDP2.0.H.264-NPMS_track3_[eng]

[upbeat dramatic music]

- [Narrator] We are surrounded

by extraordinary
feats of engineering,

constantly pushing the
boundaries of what's possible.

- Without engineering,
there'd be no modern world.

- [Narrator] Gigantic cities,

amazing infrastructure,

and ingenious inventions.

- Engineering is the key to
turn dreams into reality.

- [Narrator] To reach
these dizzying heights,

today's technology
relies on breakthroughs

made by ancient engineers.

- It's mind-boggling
how they did this.

- [Narrator] How did
early civilizations

build on such a scale?

- They raised the
bar for construction

in a way that no one
thought possible.

- The sheer engineering ability
is in itself impressive.

- [Narrator] By defying
the known laws of physics

and daring to dream big,

they constructed
wonders of the world

from gigantic pyramids

to awe-inspiring temples

and mighty fortresses.

All with the simplest of tools.

- Cannot imagine the skills

people would have needed
to build like this.

- [Narrator] Now it's possible
to unearth the secrets

of the first engineers.

- They managed to
construct edifices

that have survived
the ravages of time.

- [Narrator] And
reveal how their genius

laid the foundations for
everything we build today.

[upbeat dramatic
music continues]

[upbeat electronic music]

[water bubbling]

Water.
[water splashing]

A matter of life or death.

[upbeat electronic
music continues]

- Water is the one thing
none of us can do without.

- Without water, nothing
would be possible.

- We can't survive more than
about three days without it.

[water splashing]

- [Narrator] A modern
city like New York

consumes over 1 billion gallons
of water every single day.

Keeping the taps on

ensuring a constant flow
of clean, safe water

has been one of the greatest
engineering challenges.

- When you turn on a tap,

it's so easy to forget the
immensely complex engineering

which makes that
fresh water possible.

- [Narrator] Engineers have
built vast underground tunnels,

diverted rivers,
constructed mighty dams.

- The careful balance struck
between the forces of nature

and the engineering
required to build a dam

is pretty astounding.

- [Narrator] Giant
infrastructure
dominating the landscape.

[upbeat electronic
music continues]

Huge pumping stations.

Aqueducts defying gravity to
carry water hundreds of miles.

Machinery to turn
salt water into fresh.

And incredible
irrigation systems

bringing arid deserts to life.

Despite all this innovation,

the world still faces
a water shortage.

[loud crackling]

Population growth, agriculture,

and industry drive
ever increasing demand

for this priceless resource.

- There's more than
2 billion people

who don't have enough
water at the moment.

This problem is only
going to increase.

- Water will continue to be a
scarce and precious resource.

- [Narrator] Thousands
of years ago,

a smaller global population

meant finding water sources
wasn't usually such a problem.

But developing ways to
control and transport water

would require a great
leap in human ingenuity.

[soft upbeat music]

So how did ancient engineers
invent the technology

that led to the
birth of agriculture

and allowed ancient
empires to expand?

[air whooshing]

[soft relaxing music]

For early civilizations, the
simplest way to obtain water

was to build close to it.

- Throughout
history, settlements

have tended to be by rivers

simply because it means you've
got water easily accessible

but also it's likely that
the land next to the river

is going to be capable
of cultivation.

- [Narrator] But as
settlements developed,

living beside water
wasn't always an option.

New technology was needed.

In the 7th century
BC, the ancient Greeks

were one of the first
to tackle the problem

by building large
civic water systems.

[soft relaxing music continues]

One of Greece's
main maritime hubs

was on the wealthy
island of Samos.

And Samos had a problem,
a bone dry climate.

- One thing that its
population were really lacking

was access to clean,
safe fresh water.

- [Narrator]
According to legend,

engineers were tasked
with bringing water

to the island's main
port city of Tigani.

- The basic problem was the
nearest source of fresh water

lay miles away over a mountain.

[dramatic orchestral music]

- [Narrator] An architect
and engineer called Eupalinos

was commissioned to
get the job done.

Using simple measuring equipment
and complex mathematics,

he came up with an
amazing engineering plan.

Something never
previously attempted.

- He decided that he needed
to go through the mountain,

bore a tunnel that would go
underneath all that rock.

- [Narrator] It would mean
digging for just over 1/2 a mile

through solid rock.

The idea was to
excavate simultaneously

from both sides of the mountain.

- Building a tunnel
from either end

is an incredible
technological challenge.

- [Narrator] But ensuring both
sides met inside the mountain

was no mean feat.

- Eupalinos took two
crews of engineers

working on either
side of the mountain

with hammers and chisels,

cracking through the hard
limestone to meet in the middle.

- [Narrator] Although rumors
of this technological marvel

persisted, it was
only rediscovered
around 170 years ago.

And recently some of its
secrets have come to light.

In the 1970s,
German archeologists

spent three years
excavating the entire tunnel

and connecting aqueduct.

According to their measurements,

it was built over 570 feet
below the summit of the mountain

and was around 3,400
feet in length.

It was proof of Eupalinos's
legendary achievement.

But how had it been built?

[tools banging]

It involved more
than brute force.

[tools banging]

This called for
precision surveying.

- If you imagine
you've got two tunnels

coming towards each other,

and if they were in parallel,

they could very easily
miss each other.

- [Narrator] For Eupalinos,
the key lay with mathematics.

- He understood through geometry

that if you angle both
tunnels in the same direction,

eventually their
paths will cross.

They will absolutely meet,

there's no doubt in
that mathematically.

- [Narrator] It worked.

After nearly 10 years'
back-breaking effort,

the tunnelers finally
met in the middle.

They'd excavated well
over 15,000 tons of rock

and laid 5,000
sections of clay pipe.

Once completed,
abundant, fresh water

began to flow through
the city's fountains

and continued to do so
for over a thousand years.

[dramatic orchestral music]

[water splashing]

- Today, we have GPS

and we have all sorts of
laser measurement systems,

but he didn't have any of
those tools at his disposal.

So it's absolutely
incredible that he succeeded.

- [Narrator] Eupalinos
had earned his place

in the annals of engineering.

Even today, engineers
can struggle to ensure

the water keeps flowing.

[soft relaxing music]

In 2008, the Mediterranean
island of Cyprus

suffered a fourth consecutive
year of low rainfall.

By summer it faced a
full-blown drought.

[insects chirping]

So how could the
authorities ensure

water reached residents

and the millions of tourists
flocking there for holidays?

At first, water was shipped
in from Greece using tankers

but this wasn't viable
in the long-term.

So in the Turkish
North of Cyprus,

engineers came up with
an ambitious plan.

- They decided to pipe water
50 miles from the mainland

across the sea to the island.

[upbeat pulsing music]

- [Narrator] How
could it be done?

First step was to build a
massive new dam in Turkey,

creating a reservoir
holding over

4.5 billion cubic feet of water.

- Then came the construction

of the longest underwater
subsea pipeline in the world.

- [Narrator] Engineer's
first built anchor platforms

weighed down on the seabed.

Then they attached to
ropes with buoyancy aids,

enabling the 50 mile pipeline

to be suspended
above the seabed.

At 820 feet down,

it was safely below
fishing stocks

and shipping lanes.

Water from the
reservoir in Turkey

was then pumped through
the pipeline to Cyprus.

As a result,

the water supply to Northern
Cyprus was guaranteed.

But for one ancient civilization
across the sea from Cyprus

water supplies were
never a problem.

[air whooshing]

[soft relaxing music]

Admired for its great advances

in every area of human endeavor,

from the arts to science,
technology to religion,

its engineering accomplishments
include great monuments,

pyramids, and temples.

Ancient Egypt.

Egyptian civilization developed

along the banks
of the River Nile.

Each year around July,

the Nile would flood,
spilling over with water,

flowing down from
mountains in the south.

[water splashing]

As the waters receded,

they left behind rich soils

allowing agriculture
to flourish.

The extent of the
yearly inundation

determined how much food
would be harvested that year.

But flood levels were
always unpredictable.

- Too low, not
enough fertilization,

therefore, your
crop is inadequate.

Too much and you end
up sweeping away towns

and also ruining the fields.

- [Narrator] So how
did Egyptian engineers

prepare for either
feast or famine?

In 2016, workers constructing

the foundations of a
water pumping station

near the ancient city of Thmuis

uncovered a
mysterious structure.

[soft pulsing music]

Made from large
limestone blocks,

it was a circular well
roughly eight feet in diameter

with a staircase leading
down into its interior.

Archeologists inspected the site

and realized it was
part of a rare structure

called a nilometer.

- Nilometer was the way in which

the ancient Egyptians measured
the flood of the Nile.

- [Narrator] These
nilometer wells

were frequently located
within the confines of temples

where only the priests

and rulers had access.

How could they help
predict the coming harvest?

- Okay, a nilometer
is effectively a shaft

connected to the Nile
by a little tunnel.

And on the sides of
it, you put markings

and you look and see how high
the water's come up that shaft

and read off the numbers.

[upbeat orchestral music]

- [Narrator] Over many years,

flood levels would
have been recorded.

- They then presumably
looked at tables

drawn up over history

and be able to work out where
there would be a good harvest,

bad harvest, or
indifferent harvest.

- [Narrator] This
secret knowledge

was a source of power
in ancient Egypt.

[rocks crashing]

In the early 1970s,

Egypt's era of inundations
finally came to an end

when the Aswan High
Dam became operational.

Fully controlling
the annual flood,

it ensures water is now
available for irrigation

all year round.

The dam has almost doubled
Egypt's agricultural yield

while improving navigation
across the Nile,

a boon to the fishing
industry and tourism.

It also provides half of
the nation's power demands.

Dams have been in use
for over 5,000 years.

Today, there are over
58,000 of them worldwide.

China has the most
and recently completed

one of the biggest in the
world, the Three Gorges Dam.

[upbeat electronic music]

It's around 600 feet high,

more than 7,500 feet long,

and creates a reservoir
with a surface area

of around 400 square miles.

To pull off this dazzling
feat of engineering,

engineers had to
overcome a major problem.

- One of the biggest challenges

that engineers faced
in building this dam

was that it's still a
really major waterway

and they had to find a way
to allow ships to pass.

- [Narrator] When
the dam first opened,

ships used a series
of locks to pass.

But this added three or
four hours to journey times,

so engineers were tasked with
finding a better solution.

Result? The world's
largest elevator for ships.

Vessels enter a reinforced
concrete chamber

suspended from 256 cables
attached to counterweights.

- You sit the ship
in a kind of lift car

that's actually a
big bucket of water.

- [Narrator] When the
counterweights go down,

the chamber rises,
or vice versa.

At the top and
bottom of the lift

the chamber sits at the
same level as the river.

So when its steel gate
opens, a vessel can exit,

cutting the time a ship
takes to pass the dam

to just 40 minutes.

This brilliantly
engineered solution

is one key to the dam's success.

The other is its
hydroelectric output.

- The Three Gorges Dam

is an unbelievable
feat of engineering.

It produces so much power,

22,500 megawatts.

- [Narrator] That's enough
electricity to power

both New York and Los
Angeles every day.

But dams can also have
a negative impact.

Flooding large areas,
forcing people to relocate,

and impacting ecosystems.

[water splashing]

Dams weren't the only
means of controlling water

in the ancient world.

Engineers also came up with
other ingenious devices.

[loud crackling]

[soft orchestral music]

Although the Nile inundation

provided rich soils in
which to grow crops,

the farmers of ancient
Egypt still needed

a constant flow of water
to reach their plants.

But how could this be guaranteed
once floodwaters receded?

Canals and ditches were
dug out from the river

leading into the fields,

but engineering
solutions were needed

to then carry
water to the crops.

One such device was the shadoof,

first used for irrigation
in around 3000 BC.

- A shadoof is
basically a beam of wood

on a balance in the middle

with a bucket on one end and
a counterweight on the other

so that you could easily lift
quite heavy volumes of water

up to a higher level.

- [Narrator] When
correctly balanced,

the counterweight supports
a half-filled bucket.

It takes a bit of labor
to lower when empty,

but only minimal effort
to lift a full bucket.

Due to its simplicity, the
shadoof is still used today

in some countries
for irrigation.

But there are certain
parts of the world

where agriculture has
never been viable,

and they're growing fast.

[loud cracking]

[farmer whistling]

- Due to climate change,

we're seeing more
and more arable land

turning into desert every year.

[soft pulsing music]

- [Narrator] Yet thanks
to modern engineers,

in some places the
desert is now blooming.

And the best place to
observe this transformation

is from space.

[soft pulsing music continues]

From orbit, strange circular
forms are starkly visible

in some of the world's
driest regions.

- When you see these green spots
in the stark desert context

it's very striking
and very unusual.

It looks very out of place.

Apparently astronauts aboard
the International Space Station

use them as landmarks.

- [Narrator] These circular
areas are in fact crops.

But how can they grow in
the middle of a desert?

It relies on an
engineering solution

called center pivot irrigation.

[cheerful upbeat music]

[water splashing]

- Pivot irrigation is
essentially a system

where you look for water
deep under the ground.

So it could be up to
four kilometers deep.

And these are really, really
ancient sources of water

that have been there
for thousands of years.

- [Narrator] Once
pumped to the surface,

water flows along
an irrigation arm

powered to move around
in a wide circle.

- Water sprayed in very
specific size droplets

that can be controlled
to be accurate,

depending on the
crop requirement.

- [Narrator] This method
wastes less water.

Crops receive just
the right amount

to enable them to flourish.

[cheerful upbeat
music continues]

[water splashing]

Some scientists are concerned
center pivot irrigation

may deplete deep water reserves.

But there's no doubt
this engineering

is transforming some of
the world's driest regions.

Getting water to
where it's needed most

has always been an
engineering challenge.

Nowhere more so than
for one ancient city

with a population of over
a million thirsty souls,

all in need of fresh water.

[enchanting orchestral music]
Ancient Rome.

Roman engineers were renowned

for their ability to
control the flow of water.

[water splashing]

Digging deep tunnels to
transport it many miles.

Building mighty structures
across ravines and valleys

to keep it flowing.

[dramatic orchestral music]

Constructing luxurious
heated public baths

and lavish fountains.

- The Romans developed amazing
water control technology.

This massive network
of interconnecting

sewers and aqueducts and drains.

[dramatic orchestral
music continues]

- [Narrator] Roman techniques
for the collection,

storage, and delivery of water

over huge distances
were unsurpassed.

Their engineers developed a
host of innovative technologies.

- The Romans are the
masters of providing water

wherever and
whenever it's needed.

- [Narrator] But why
go to such lengths?

- Like their famous
road network,

controlling water
allowed the Romans

to develop and supply their
rapidly increasing population.

- The Romans knew that
water was fundamental

to the success of
their civilization.

- [Narrator] Without a
reliable water supply,

the entire continent-spanning
empire could be threatened.

- A couple of days
with no water, you
have complete anarchy.

- [Narrator] But what were the
technological breakthroughs

that kept water flowing
throughout the Roman empire?

[water splashing]

[pulsing orchestral music]

By the 2nd century AD,

ancient Rome had become the
largest city in the world.

Home to well over
a million people.

To expand further, it
desperately needed a constant,

safe, and guaranteed
supply of water.

- Rome is built
on the River Tiber

and the Tiber
provides some water,

but as Rome expands,

as it becomes one of the
greatest cities in the world,

it needs to find additional
fresh water from elsewhere.

- [Narrator] So where did this
additional supply come from?

A vital clue was found

during construction
of the city's Metro.

[subway whirring]

- It's one of the
smallest in Europe.

And part of the reason for this

is because the ground
underneath the city

is so rich in
archeological remains.

Every time a new
tunnel is planned,

they have to excavate more area

and discover more things
which have to be investigated.

- [Narrator] In 2016, while
extending one of the lines,

workers stumbled across
some impressive remains

over 100 feet in length.

After careful analysis,

archeologists concluded
they were part

of the oldest known Roman
aqueduct, dating back to 312 BC.

- The first aqueduct to be
built in Rome is the Aqua Appia

which was built by the
censor at the time,

Appius Claudius Caecus.

- [Narrator] At this early
point in its history,

Rome was at war with a
tribe from Southern Italy

called the Samnites.

- The Romans feared
that the Samnites

might pollute the River Tiber,

which was their main
source of water.

- [Narrator] But the city's
nearest alternative supply

was a natural spring
around 10 miles away.

[water splashing]

Without the aid of
mechanical pumps,

how would engineers
bring this water to Rome?

[dramatic orchestral music]

- The solution was
to build an aqueduct,

to rely on gravity, to
create such a gentle slope

that that water would trickle

all the way into
the city itself.

- [Narrator] The Aqua Appia

was built with an
incredibly shallow gradient.

less than half a
degree of descent.

It was a great test
of engineering skill.

Too much of an incline,
and the fast-moving water

would erode the fabric
of the aqueduct.

- Too little of a slope,
than the water itself

can remain stagnant,

so it's an incredible
engineering challenge.

- [Narrator] To get there
gradient just right,

engineer's used a device
called a chorobates.

Similar to modern spirit levels,

it was a bench with
attached plumb lines

and a groove carved into
the middle containing water.

Two site holes at each end

enabled a measurement to be
taken using a ranging pole

around 40 feet away.

By raising and lowering
the legs of the bench,

the surveyor was able to plot
the gradient of the aqueduct.

But the aqueduct also
had to be protected

from possible attack.

So the Aqua Appia would be
constructed mostly underground.

[tools banging]

To do this, the Romans used
the so-called qanat method.

Well-like shafts were dug at
consistent vertical intervals

until they reached
the desire depth.

Cranes using pulley systems

were used to lower
building materials in

and debris from the tunnels out.

Workers then dug
horizontal sloping tunnels,

linking the adjacent
shafts together.

And it worked.

[dramatic orchestral
music continues]

The Appia supplied
the city of Rome

with an estimated 16 million
gallons of water per day.

[dramatic orchestral
music continues]

[water splashing]

- There were around
700 taps in the city

and about 200 of those were
used for private purposes.

And the rest of those
taps were for public use

for public baths, for fountains,

and for draining
the streets of Rome.

[soft enchanting music]

- [Narrator] Over a period
of around 500 years,

a total of 11
aqueducts were built

bringing water to Rome
from up to 60 miles away.

To this day, the Aqua Virgo,

an aqueduct
constructed in 19 BC,

supplies water to one of
Rome's most famous landmarks,

the Trevi Fountain in
the heart of the city.

[fountain splashing]

[water splashing]

[relaxing orchestral music]

As time went on, the Romans
constructed further aqueducts.

Some amazing feats
of engineering right
across the empire.

- Romans took their water
engineering prowess with them

wherever they went, creating
magnificent structures

from Spain to Syria,

showing off not only
their technical brilliance

but the amazing power
of water itself.

- [Narrator] Many structures
still stand today,

testament to the prowess
of ancient engineers.

The Segovia aqueduct in Spain

was built during the second
half of the 1st century.

[dramatic orchestral music]

While the Valens aqueduct
reached over 150 miles in length

and provided water
to Constantinople,
modern day Istanbul.

But one of the most
impressive structures of all

was built as part of an aqueduct
found in Southern France

near the town of Nimes.

The Pont du Gard.

[dramatic orchestral
music continues]

- The Pont du Gard is
a Roman aqueduct bridge

built in the 1st century AD.

It remains an amazing
spectacle of Roman engineering.

- [Narrator] Designed to carry
water over the River Gardon,

this marvel stands 160 feet high

and features three
vertical rows of arches.

So how did engineers build

one of the tallest of
all Roman structures?

[air whooshing]
[tools clanging]

Numerous scientific
studies have revealed

that an impressive
volume of rock was needed

to complete the Pont du Gard.

- A huge amount of rock
went into its construction.

Over 21,000 cubic meters of rock

which weighed over 50,000 tons.

- [Narrator] Moving
this huge volume

of material into position

would require a combination
of ingenuity and muscle power.

[tools clanging]

- The Romans invented
the Polyspaston crane

which allowed them to raise
up immensely heavy stones.

- [Narrator] The key
element of this crane

was a treadwheel in the center

that acted very much
like a hamster wheel.

A crane operator would scamper
around inside the device

to power its lifting mechanism.

A rope attached to a pulley
was turned onto a spindle

by the rotation of a wheel,

allowing the device to
hoist or lower the load.

In comparison, for
the ancient Egyptians

it took a large
number of men to haul

the 2.5 ton stone blocks

used to build the pyramids.

It's believed the
Polyspaston crane

would be much more efficient,

as moving the same 2.5 ton block

would require just a small
number of workers to lift it.

- Incredibly, human
powered treadwheel cranes

remained in use until as
recently as the 1900s.

[crane clicking]

[air whooshing]

[dramatic orchestral music]

- [Narrator] Once the
Pont du Gard was finished,

an estimated 44 million
gallons of water

float across it every day.

[water splashing]

[dramatic orchestral
music continues]

And it has stood
the test of time,

surviving some serious flooding
over the last 2,000 years.

[water rushing]

[soft pulsing music]

One extreme event in September
2002 in Southern France

claimed the lives of 21 people

and caused millions of
dollars of damage to towns

and villages along
the River Gardon.

Over the past 10 years,

80 to 90% of all natural
disasters worldwide

have been a result
of floods, droughts,

tropical cyclones, heat
waves, or severe storms.

Thanks to climate change,

floods are increasing in
frequency and intensity

and may cause even greater
damage in years to come.

- Cities and societies
across the world

are having to come up with
ever more ingenious ways

of coping with that danger.

- [Narrator] The
solution may lie

with novel large-scale projects.

[air whooshing]

- London, for example,
is very low-lying

and is seriously under
threat from rising sea levels

on the one hand, and
floods on the other.

- [Narrator] But fortunately,
London is a place

where engineering
has led the way.

In the early '80s,
a barrier was built

on the city's Eastern boundary.

[pulsing electronic music]

It spans 1,700 feet, the entire
width of the River Thames.

- The Thames barrier protects
London from storm surges

coming from the North
Sea into the Thames.

And essentially, it's made
up of a series of gates.

- [Narrator] A total of 10
gates create a steel wall

protecting an area of
around 50 square miles.

Each one is just
under 66 feet tall,

weighs over 3,600 tons,

and can hold back a load
of up to 9,000 tons.

[air whooshing]

Ordinarily, six of these
gates rest on the riverbed,

but they're always on
standby for a storm surge.

- If there's the danger
that the river levels

are rising, then the
gates rotate into position

and then stop the water
from flooding into London.

[birds chirping]

- [Narrator] So far,
the Thames barrier

has been raised nearly 200 times

in order to prevent
flooding in Central London.

As well as finding ways
of holding water back,

engineers have come up
with spectacular ways

to keep water in.

Water is heavy.

Fill up an Olympic-size
swimming pool,

[water splashing]

and you're talking about
around 600,000 gallons,

making certain spectacular
modern structures a challenge.

- When constructing swimming
pools on top of buildings

there is no room for
engineering structural errors.

- [Narrator] At the Marina
Bay Sands Hotel in Singapore,

an infinity pool
perches 55 stories up.

Supported across the
top of three towers,

including the lookout decks,

it's longer than the Eiffel
Tower laid on its side.

[soft upbeat music]

And at the Golden
Nugget, Las Vegas,

is a 200,000 gallon
shark-filled aquarium.

Fearless swimmers shoot
down a three-story

enclosed water slide,

carrying them within
inches of the sharks.

[water splashing]

[pulsing dramatic music]

Large pools are nothing new.

Public baths had been a feature
of towns in ancient Greece,

but it was the Romans
who went crazy for them.

Baths for washing and relaxing

were a common feature of Roman
cities throughout the empire.

- Public baths were
essential in cities

because the majority of
people would not have had

bathrooms in their houses,

unless you were
extremely wealthy.

- It was very much a
communal enterprise

where all sections of
society sat together.

- It was a duty almost

and it wasn't just about
keeping yourselves clean.

This is where people
went to discuss,

it's where politics happened,

it's where life was lived.

- [Narrator] At one point,

there were over 850 public
baths in Rome alone.

Some of these complexes took
on monumental proportions.

Feats of engineering built
with vast colonnades,

wide-spanning arches,
and spectacular domes.

The interiors were
often sumptuous affairs

with fine mosaic floors,
marble-covered walls,

and decorative statues.

[dramatic orchestral music]

Within the baths
were separate rooms

containing pools at
varying water temperatures.

The frigidarium, cold pool.

Tepidarium, for warm.

And caldarium, the hot pool.

- The Romans would start
off in the tepidariums,

get ready for the caldarium.

And then, at the end of
that bathing process,

you would go into
the frigidarium

to close up your pores again

and get you ready
for the outside.

- [Narrator] But
how did engineers

control the temperature
of the rooms and water?

[water splashing]

Early baths were heated
with simple braziers

but from the 1st century BC,

a more sophisticated
setup was deployed.

An innovative and complex
system known as a hypocaust.

[soft dramatic music]

Furnaces attached to the
bathhouses produced hot air.

This was fed below
elevated floors

and up through hollow
walls, warming the rooms.

Water was heated in boilers
positioned above the furnaces

before being piped
into the pools.

- Very early, very effective

form of central heating.

- But underneath all the glamor,

it would have been slaves
feeding these furnaces

which was hard work.

[fire crackling]

- [Narrator] The
baths of Caracalla

in the South of Rome are
among the best preserved.

Constructed in the 3rd century,

their water came from the
57 mile long Aqua Marcia,

Rome's longest aqueduct.

Around 50 furnaces were
needed to heat the complex.

The baths had four entrances

and could accommodate as
many as 8,000 daily visitors.

As well as spas and
pools, Caracalla had
shops and eateries.

- They were the place
you went to hang out,

to chat, to meet your friends,

to gossip, to see
who's wearing what.

It was the place
to see and be seen.

[soft relaxing music]

- [Narrator] Water may
be vital for bathing

but it also plays a more
hidden role in human hygiene.

As what goes in must come out.

- One of the interesting
things about fresh water

is that on the one
hand it provides life,

but on the other hand, it
can be incredibly dangerous

if wastewater is not
dealt with properly.

- [Narrator] It takes vast
engineering infrastructure

to deal with the millions
of tons of sewage

produced by large cities.

[water splashing]

The average human produces

over 320 pounds of
excrement a year.

[toilets flushing]

- If we don't have
proper sewage systems

to take this waste away,

then our cities
and our settlements

become ridden with disease.

[upbeat electronic music]

- [Narrator] And water engineers
now face a growing problem

in sewage systems
across the world.

Fatbergs.

London, Belfast,
Denver, and Melbourne

are just a few of the cities
where these monstrosities

have been discovered
in recent years.

[water splashing]

- Fatbergs are massive
deposits of congealed fats

and other waste.

- [Narrator] New York
City has spent $18 million

over five years
on tackling them.

[upbeat electronic
music continues]

And in one London sewer,

an 800-foot long
fatberg was discovered,

weighing an estimated 130 tons,

the size of 11
double-decker buses.

- It's down to workers
called flushers

to get rid of fatbergs.

- [Narrator] These
fearless individuals

wear protective clothing
and carry gas monitors

to ensure the air
is safe to breathe.

They're tasked with manually
breaking apart the fatberg,

aided by suction
pumps and power jets.

[water splashing]

But blockages are a problem
ass old as sewers themselves.

[soft upbeat music]

In ancient Rome, slaves were
reportedly sent underground

to clear the drains.

And it seems the
baths-obsessed Romans

may not have been quite as
clean as previously thought.

- Roman cities would
have been filthy.

And we think that Roman
pavements in many cities

might've been built up very high

so that Romans walking around

didn't have to go
anywhere near the gutters.

- [Narrator] Open drains
were filled with waste

and raw sewage, causing
an unimaginable stench.

But in the 6th century BC,

Rome's engineers
came to the rescue

with a huge
infrastructure project.

- The Cloaca Maxima,
or the great drain,

was one of the earliest examples
of Roman public sanitation.

- The Cloaca Maxima began
as a type of open canal

but it developed
into one of the most

complex sewerage systems
in the ancient world.

- It was constructed as a stream
which ran through the city,

draining the city
of excess water.

- [Narrator] The Cloaca Maxima

originally measured over 320
feet long by 15 feet wide

and stood 11 feet high.

- The Romans realized that
they had to cover it up

to protect the city
from nasty smells.

- [Narrator] But this presented
a major engineering problem.

The drain would have
to be made waterproof.

[water splashing]

Roman engineers found a solution
with a new type of concrete

containing lime and pozzolana.

[Volcano exploding]

Pozzolana derives
from volcanic ash

and when combined
with lime and water,

creates a strong concrete mix.

But the Romans also discovered

a unique advantage to
their new formulation.

Unlike regular concrete, it
could set in wet conditions.

- The resulting
concrete that they made

could actually set underwater

and that was a really
special feature.

- [Narrator] This technology
meant that as Rome grew

so too could its sewage system.

The great sewer served the
city for over 2,400 years.

And even today is still in
use to carry stormwater away

into the river Tiber.

And Roman civil
engineering projects

weren't limited to the capital.

- The Romans built them

in other parts of
their empire as well

to make sure that
those towns and cities

were well protected
from pollution

and from the health issues
that come with having

inadequate hygiene standards.

- [Narrator] Unfortunately,
these improvements

didn't survive the
fall of the empire.

[soft pulsing music]

Down the centuries, Roman
advances in sanitation

were slowly forgotten.

[water splashing]

Only a few cities,
including Paris,

preserved sections of
their Roman sewage systems.

- What happens in the
Middle Ages is that

in most cases these central
systems of waste management

have broken down.

[footsteps crunching]

- The towns, the cities
of Medieval Christendom

were the most revolting places.

It was a massive stinkpot.

[water splashing]

[footsteps splashing]

[soft pulsing music continues]

- Rats thrived among the
excreta and epidemics of plague

and cholera broke out,
killing millions of people,

about 25% of the Medieval
European population.

[wheels clicking]

[air whooshing]

- [Narrator] But on a hilltop
in the heart of Granada

in Southern Spain,
engineers built a structure

that bucked this trend.

[soft ethereal music]

An oasis of cleanliness amid
the general Medieval muck.

This 13th century palace
was named the Alhambra.

- It's one of the
great sites of Spain.

It's one of the moments
where you can go

and stand and feel
closest to Islamic Spain

and you can see just
what a rich and vibrant

and exciting society that was.

- [Narrator] The Monarch,
Mohammed ibn Alhamar,

at that time had a vision of
transforming a dusty hilltop

into a lush oasis with
a palace at its heart.

[water splashing]

So how was this
dream made a reality?

[soft ethereal music continues]

First, engineers built
a canal to carry water

from a river 3.5
miles up stream.

This was channeled
into large reservoirs

on the hill above the Alhambra,

from where it flowed down
through a series of channels

and pools to the palace.

- Inside the Alhambra is a
complex network of channels

for the water to flow
just using gravity.

- [Narrator]
However, water supply

was seasonal and sporadic.

So a collection tower
was used to make sure

there was always enough
water for the gardens,

fountains, and baths,
allowing the monarch's vision

to be realized all year round.

[water splashing]

- It was well-watered.

It was light.

It was dazzling.

It didn't smell.

It must have seemed to travelers
like paradise on Earth.

- [Narrator] Just
as ancient engineers

struggled to move water uphill

and transport it ever
greater distances,

today it still remains a
technological challenge.

[soft rock music]

Los Angeles, home to
over 12 million people.

- There are an awful lot of
people who want to live there

and that means that
they need water

to support their irrigation,

their agriculture, their lives.

- [Narrator] Average daily
water consumption in L.A.

is a colossal 131
gallons per person.

In such a dry part
of California,
essentially a desert,

where can so much
water be found?

For years, Los Angeles
relied on aqueducts

to transport water from
rivers many miles away.

[soft rock music continues]

But as the metropolis grew,

engineers had to
look further a field.

- In the 1960s
construction began

on a new aqueduct system.

- [Narrator] This
was infrastructure

on a totally different scale.

Stretching over 400 miles,

it would be the world's
longest aqueduct.

Beginning just east
of San Francisco

in the wetter
north of the state,

the California Aqueduct

would wind its way
south towards L.A.

But one major problem
stood in the way.

[soft pulsing music]

- The engineers faced
a significant challenge

at the end of the
water's journey to
get it to Los Angeles.

- [Narrator] The
Tehachapi Mountains.

There were two choices.

Go through the mountain
range or go over it.

Above ground seemed the
cheaper and quicker option,

but how would
engineers defy gravity

and move such enormous
quantities of water uphill?

- Essentially,
engineers had to build

one of the biggest water lifts

to get the water
over the mountain.

- So to do this, they
used enormous pumps

that had 80,000 horsepower.

- [Narrator] 14
pumps were installed

requiring around 60
megawatts of power,

enough electricity
for a small city.

[soft pulsing music continues]

The aqueduct's main
channel completed in 1973

supplies water to
over 26 million people

and 3/4 of a million acres
of agricultural land.

Today's engineers
may have mastered

the art of controlling water,

but humans remain slaves
to this vital resource.

And it's likely
the world will face

ever more severe water shortages
in the decades to come.

Already around
one person in nine

lacks access to clean,
affordable water.

And as the population
grows, so too does demand.

It could be a catastrophe
in the making.

- Finding and
distributing fresh water

is continuing to be
a big challenge to us

in the modern world.

- The 20th century
saw war over oil.

The 21st century
could very well be

the century in which
we see war over water.

- [Narrator] But engineering
solutions could be at hand.

- Distillation is a technology
which is really important

for being able to
provide fresh water.

Essentially turning salt
water into fresh water.

- Desalination manages
to make something deadly

into something that
can bring life.

- [Narrator]
Currently this method

requires a lot of
energy, making it costly

while adding to global
greenhouse gas emissions.

As ever, the world is
looking to engineers

to find technological solutions,

ensuring the planet's
taps continue to flow.

[soft dramatic music]

From the earliest tunnel
systems in ancient Greece

to the simple tools that
irrigated the Nile flood plains,

the water infrastructure that
dominated the Roman landscape,

and intricate heating systems

that warmed their public baths.

Without the amazing innovations
of ancient water engineers

disease and thirst
may have held back

the development of civilization,

and the modern luxury
of fresh water on demand

would not be possible.

[water splashing]

Thanks to engineers,
safe and clean water

may one day be
available for all.

[dramatic orchestral music]