We'll show you how the law can help those in need get what they need.

As populations and temperatures rise, how will the law stop a crisis?

And... can the law stop businesses taking the water you need to live?

There are more than 7.8 billion of us on the planet.

That number is going up.

We're using more and more water,

but there's only a limited amount available.

Cape Town, South Africa:

water levels in reservoirs started dropping in 2015.

In 2017, people started talking about Day Zero,

a possible time when taps would need to be turned off.

Real worries that a city of four and a half million people

would need to queue in the streets to get water.

The Dead Sea in Jordan:

30 years ago, water reached this motorway,

but rivers were diverted for farming.

Climate change added to the problem

and now the sea itself is at risk

and the soil is drying out so much,

the structure of the ground is breaking.

Huge sinkholes have opened up, wrecking roads and homes.

This is the kind of problem that causes other problems.

People may fight for water,

or run to another country for help.

How can the law help?

We spoke to Dr Paul Orengoh,

from the African Ministers Council on Water.

He explained which laws are in place

to help share this vital resource.

We have conventions and protocols

that promote universal access to clean water

and I would consider the United Nations Sustainable Development Goals 2030

to fit under this.

However, these international conventions,

protocols and political commitments are loosely structured

in a way that countries are not forced to commit to them.

So, in such a case, with a weak framework as that,

then it becomes a matter of choice upon individual countries

to pick whether they use them or not.

The United Nations Sustainable Development Goals

encourage sharing water, but they aren't legally binding:

they don't force countries to do so.

Which laws need to be developed?

Water issues are usually very local in terms of challenges and opportunities,

and each local set-up has their own unique set of features.

So, why do we need a global commitment

to be able to influence the local legislation?

I think laws will need to be done

within the sensitivities of local context,

to be able to have been effective enough

to serve the agenda of universal access to water.

While we need a global commitment to solve the water crisis,

every country is different.

So, they need local laws that work in their context.

The water crisis will make people leave their homes;

do they have the right to seek help in other countries?

We currently do not have laws or policies

that provides for climate-induced migration

or movements or misplacements of persons

that happens as a result of climate change.

Unfortunately, that is the current situation

but laws and policies are needed,

especially to protect the very poor,

who bear the burden of climate change.

Unfortunately, there aren't laws directly protecting people

who have to leave their homes due to lack of water.

People currently don't have the right to seek refuge from climate issues.

Do we have enough climate laws to manage the water crisis?

At the national level and regional level,

as well as global level, these kind of laws are needed.

Within the context of climate change, of course,

what is done at the national level

feeds into regional level and to the global level.

So, there's no kind of one-way approach to this.

It has to be done across the levels.

Climate change is a global problem,

so we need laws at a global level.

But, to get things done, we really need laws

at a smaller, regional and national level too.

Paul says there aren't many international laws

protecting people forced out of their homes to find water,

and that local laws need changing too.

Of course, water isn't just vital for drinking.

We use it in our factories in huge amounts.

People depend on work and water to survive,

so what could the future hold?

Early 2021...

and Taiwan's biggest reservoir, Tsengwen,

was at its driest in years.

Other reservoirs in Taiwan are also thirsty,

including this one in the north, which supplies water

for Taiwan's $100 billion semiconductor industry.

The world's largest contract chip maker, TSMC, is nearby.

It and other semiconductor companies

need a lot of water to spray clean the silicon wafers

that go inside tech gadgets...

using up to 170,000 tonnes of water a day.

The government has stopped irrigating

thousands of hectares of nearby farmland.

That has left farmers like Chuang Chen-deng

worried about his rice fields.

You can give us water for two days a week

or one day – farmers will find a way.

But now, they've completely cut our water.

Farmers can't find a way out.

You're focusing entirely on semiconductors.

Chip maker TSMC planned for the worst.

They brought truckloads of water, extracted from construction sites,

and increased the amount of water they recycle and reuse.

Experts, however, warned that even after this drought,

tough action is needed to address the causes of Taiwan's water shortages.

So, with different groups all needing water,

we found out more from Mark Zeitoun,

Professor of Water Security and Policy

at the University of East Anglia in the UK.

He explained how the lack of water –

also called water scarcity – is a complex issue.

Well, actually, there are two types of scarcity:

one – the most common – is what we call biophysical scarcity.

That's when it doesn't rain enough and when we're counting on the rains.

The other type of water scarcity,

which is much more important, is called social scarcity.

That's scarcity that comes from that fact that we deny water

to people who can't afford it, or if they are the wrong nationality.

It has nothing to do with how much rain falls on the area.

There are two types of lack of water for law to look at.

Biophysical scarcity is lack of rain.

Social scarcity is when people are denied water by others.

Is international law or national law more helpful when it comes to water?

It's all about enforceability – I mean,

national law in general can be enforced:

you have a police force, you have a legal system,

you have courts, you have prisons.

International law and international water law cannot be enforced:

I mean, there is no global policeman.

I don't know of any state would be welcomed as a global policeman

and that's probably a good thing.

But, because the international water law cannot be enforced,

that means violations of international water law can continue,

sometimes without any consequences.

National laws are more likely to have a system of enforcement

when it comes to a lack of water,

because international law has no international enforcement agency.

The other good thing about international water law is

it tells you how to distribute the resources

that are transboundary or that are international.

It doesn't say that, if there are three countries involved,

that each country gets one third;

it says that each country should use the waters

in an equitable and reasonable amount.

And then it gives a definition of equitable and reasonable,

stating how much...

how many people are dependent on the water resources,

what's the economic value of the water resources

and are there alternative water resources?

International law regulates cross-border disputes,

where things like lakes and rivers cross borders between countries.

It can make sure countries share water fairly.

International law also has a lot to say about human rights.

Does this help?

Yes, most definitely. The human right to water can help for...

to deal with social water scarcity.

I mean, if... if a country recognises in its national legislation

that the right to water cannot be denied

then the government or the companies that provide you water

cannot turn their taps off, even if you don't pay for the water.

This is the case in the UK:

the UK government has recognised the right to water

and so even the private companies here cannot turn your taps off.

The human right to water helps people in many countries

get the water they need to drink.

Additional protection can be gained

if countries have included it in their own laws.

We've seen that international law has gaps

when it comes to making sure that people have enough water.

But, because international law says everyone has a human right to water,

even as supplies are drying up,

people should be able to rely on that right.