In rich countries you just take the toilet for granted.

It's magical that there is a sewer system bringing water in,

taking away the waste and it all gets cleaned up in a processing plant.

However, for the poorest two and a half billion in the world,

they don't have this.

It's unaffordable.

We can't build that for everyone in the world.

For some of the poorest, their toilet may look like this:

a pit latrine.

The waste here is not processed.

It's still going to get out into the community.

They smell terrible!

But everybody should have great sanitation.

A toilet in their house that is comfortable and doesn't smell awful.

Not only does a toilet make your life comfortable,

getting rid of that waste is key to human health.

It's unprocessed waste that causes most of the diarrheal diseases.

It ends up with lots of kids being malnourished.

So how do we solve this?

Well some scientists that I work with

said that we should challenge the world

to come up with a way of taking the waste and processing it locally.

We call this the program to reinvent the toilet.

Several reinvented toilets are being tested right now in Durban, South Africa.

Durban's a good place to run these tests

because the city is growing fast,

and many people there don't have modern sanitation

which means that even if they have access to a toilet,

the waste can get into the environment and make people sick.

A typical toilet needs water,

but many of the new approaches don't require any water at all.

Some of them don't need electricity either.

Others run on solar power.

All of them remove the pathogens from the waste.

And most importantly,

they don't have to be connected to the city sewer system.

I'm optimistic that eventually we'll find approaches

that make great sanitation available to everyone.