The world population is predicted to grow from 6.9 billion in 2010 to 8.3 billion in 2030 and to 9.1 billion in 2050.
At the same time, urban population is projected to increase by 2.9 billion, to a total of 6.3 billion in 2050.
Sources: WWDR 2012
Today, one in two people on the planet live in a city.
93% of the urbanization occurs in poor or developing countries, and nearly 40% of the world's urban expansion is growing slums.
Source: UN-HABITAT 'State of the World's Cities 2010-2011' report
Slums are projected to grow by 27 million people per year.
In Africa and Asia, the urban population will double between 2000 and 2030.
5 million people are joining the urban population in the developing world each month.
827.6 million people live in slums, often lacking adequate drinking water and sanitation services.
One of four city residents worldwide, 194 million in total, lives without access to improved sanitation facilities.
Every second, the urban population grows by 2 people.
27% of the urban population in the developing world does not have piped water in its house.
A lack of safe water and sanitation in cities leads to cholera, malaria and diarrhoea.
Today 493 million people in cities share their sanitation facilities. In 1990 this number was 259 million.
Over 80 per cent of wastewater worldwide is not collected or treated, and urban settlements are the main source of pollution.
Source: WWDR, 2012