we'll show you how the law aims to protect people's human rights

and set up new frameworks for a new world.

What could the increasing demand for water do to society?

And how can the law help?

Plus – building for the future...

how the law will provide support to vital technology.

The need for water globally is expected to increase

by 55% between 2000 and 2050.

Much of the demand is driven by farming,

which takes 70% of global freshwater use.

Food production will need to grow by 69% by 2035

to feed the growing population.

And the quality of our water is getting worse.

Pollution from industry and the plastic we throw away

are poisoning the limited amount we have.

All that could mean disagreements over water could get worse.

The Grand Renaissance Dam on the River Nile:

Ethiopia built it to create electricity.

But downstream, Egyptians are worried

it will cut their water supply

and threaten the existence of their country.

This is the Mekong River:

eleven dams sit on top of it as it passes through China.

But some countries further down the river

have said they're worried China could use those dams

to cut their water supply.

And this is just the start.

What can the law do to help with the future of water?

We spoke with Francesco Sindico, from the University of Strathclyde,

who explained why having a right to water

doesn't mean free water in the future.

Everybody has a human right to water,

so countries do have to do something.

But, let's be careful – human right to water

doesn't mean 'water free for everybody'.

What it means is that the countries have to do everything they can

to give affordable water – access to water –

to all their people.

The human right to water only means

countries have to give affordable access to water,

not free water for everyone.

He explained one part of international law

which helps look after the world's future.

International law has a rule called the No Harm Rule,

which says that you cannot do an activity

that will cause significant damage to your neighbouring country,

and that applies also water.

But one thing is very important: you don't only have surface water,

you also have groundwater

and it's much more difficult to see when that is being polluted

or when it's being overexploited.

States are meant to follow the 'No Harm Rule',

which is a principle of international law

which stops countries harming others –

and that includes water supplies.

Does he think that – and other current laws – are enough?

International law has to harden their approach

to our human right to water

and especially the relationship between water and climate change,

because that's really where the future generations have more to lose –

but also to gain if international law goes in the right direction.

Francesco wants water and climate change laws

to be more connected and to be tougher in the future.

But won't small countries always come off worse

when it comes to these disputes?

This is where we slip from international law

to international politics,

so clearly a smaller state will have less power

to enforce a decision of an international court.

However, no country, however big,

likes to see its name tarnished

by having violated the law.

When it comes to court cases,

big countries might have more power

but they don't want to get a reputation for breaking international laws.

The 'No Harm' principle protects our future access to water,

but Francesco said the law might need to be made stronger in the future.

So, in the future how can the law help people

on the hunt for ever more water?

A city that's sinking:

this is Jakarta, capital of Indonesia.

It's hard to imagine, but parts of Jakarta

are dropping by 25cm a year.

So much water has been taken from the ground under the city,

that the surface is collapsing into the space it leaves behind.

Can the law stop this happening in other growing cities?

Here's another solution:

there's something like a billion trillion litres of water on Earth.

Most of that is salty sea water, which you can't drink.

But this is a desalinisation plant,

which makes seawater drinkable.

This technology is still expensive,

but technology improves all the time.

The challenge for the law might be

making sure that countries with water

share it fairly with those who need it most.

To find out how the law could be used to share this,

and any other new technology,

we spoke to Mark Zeitoun,

Professor of Water Security and Policy

at the University of East Anglia in the UK.

He wasn't sure countries could be forced to share.

I don't think international water law could ever be enforced to that degree,

but I would certainly like to see more fair water sharing.

I think that comes about through soft law:

through persuasion and through diplomacy, rather than enforcement.

I think that's where we should lay our hopes.

He thinks diplomacy and talks will be used to share water;

it would be too hard to legally force countries to do so.

What about stopping countries

drying out their own ground, like in Jakarta?

If the boreholes are tapping into water

that's only within that country, then international water law has no bearing.

A country has the right to do what it wants to

with the water resources that are strictly within its territorial limits.

But if those boreholes take water from an aquifer,

or the groundwater from across the border,

then international water law certainly could... can be of help.

If water is taken across national borders,

international law could help,

but if a country is only using water from within its territory,

other countries can't stop them.

Looking to the future, what laws could help us

  share the water we do have?

So, international water law is not perfect,

but I think it's the least worst measure of fairness that's out there.

I don't think that any new institution has to be set up

to try to govern international water conflicts,

you know, in Latin America, or in Asia or in the Middle East.

He doesn't think any new institution or group needs to be set up:

international law is good enough to handle conflicts.

We've seen that there aren't many international laws that

directly make sure the future of our water supplies are safe.

However, the international laws that we do have,

such as the right to water and the No Harm principle,

should be strong enough, with work,

to protect us all.