There are 2.5 billion people living on the planet without access to basic sanitation.

As a result hundreds of children die from diseases such as diarrhoea every day, and women and children risk personal safety when they perform the simplest of human functions.

In this week's Costing The Earth Dr Kat Arney looks at ways to allow everyone to have access to safe, clean, environmentally friendly toilets.

She visits a toilet festival in London to find out about toilet designs that can be applied to every environmental condition across the globe: toilets that require no water, toilets that can turn waste into an asset in the form of fertiliser and toilets filled with waste-eating worms in a quest to design a toilet for the 21st Century.

Presenter: Dr Kat Arney