Millennium Development Goal 7: Ensure environmental sustainability
Target: Halve, by 2015, the proportion of people without sustainable access to safe drinking water and basic sanitation
Sanitation, which is critical to safeguarding against infection and undernutrition, is an area that urgently requires greater attention. Although global sanitation coverage has increased from 54 per cent in 1990 to 62 per cent in 2006, almost half of the developing world’s population – approximately 2.5 billion people – continues to live without access to improved sanitation facilities.

Source: UNICEF and World Health Organization (WHO), Joint Monitoring Programme
Reference:
http://www.unicef.org/rightsite/sowc/pdfs/SOWC_Spec%20Ed_CRC_Main%20Report_EN_090409.pdf