Virtually all governments accept that settlements with more than 20,000 inhabitants are urban centres but disagree about where to draw the line between urban and rural for settlements with fewer than 20,000 inhabitants. Some classify all settlements with only a few hundred inhabitants as ‘urban’ while others consider most or all settlements with up to 20,000 inhabitants as ‘rural’. This has significance for two reasons: a very high proportion of people live in settlements with between 500 and 20,000 inhabitants; and their designation as urban populations generally means more government structures and improved provision for water and sanitation.

Roughly 3% of the earth’s land surface is occupied by urban areas, with the highest concentrations occurring along the coasts and waterways.
The historical importance of water as a means of transport as well as a resource has meant that inland water and river corridors have been important in determining the spatial organization and distribution of human settlements.

During the 20th century, the world’s urban population increased more than tenfold, while rural population increased but twofold.

Today, 50% of the world’s population lives in urban centres, compared to less than 15% in 1900.

In most urban areas in low- and middle income countries, between 25% and 50% of the population lacks provision for water and sanitation of a quality that greatly reduces the risk of human contamination with faecal-oral pathogens.

In 2000, more than 900 million urban dwellers (nearly a third of all urban dwellers worldwide) lived in slums. A slum dweller may only have 5 to 10 litres per day at his or her disposal. A middle- or high-income household in the same city, however, may use some 50 to 150 litres per day, if not more.

In sub-Saharan Africa, 83% of the urban population and 46% of the rural population have access to a water supply.

In order for the Millennium Development Goal related to drinking water and sanitation to be met by 2015, 961 million urban dwellers must gain access to improved water supply, and 1 billion to improved sanitation.

The proportion of households in major cities connected to piped water (house or yard connection) is:

• World: 94%
• Africa: 43%
• Asia: 77%
• Europe: 92%
• Latin America and the Caribbean: 77%
• North America: 100%
• Oceania: 73%

  The proportion of households in major cities connected to sewers is:

• World: 86%
• Africa: 18%
• Asia: 45%
• Europe: 92%
• Latin America and the Caribbean: 35%
• North America: 96%
• Oceania: 15%.

Information from:
1st United Nations World Water Development Report ‘Water for People, Water for Life’ (2003)
the 2nd United Nations World Water Development Report, ‘Water, a shared responsibility’ (2006)

Source: UNESCO Water Portal, October 2006