The Joint Monitoring Programme of WHO & UNICEF regularly publishes reports on coverage in all countries of "improved" water supplies and sanitation (the JMP definitions of "improved" water supplies and sanitation are given here).

JMP reports published in: 2000  2004  2005  2006  2008  2010

The latest information for all countries is given on the JMP website.

UN-Water's Global Annual Assessment of Sanitation & Drinking Water(GLAAS) reports: 2008  2010

Other reports and papers:
Water Monitoring: Mapping Existing Global Systems & Initiatives (FAO, for UN-Water Task Force on Monitoring, 2006)
Status of Implementation of CSD-13 Policy Actions on Water and Sanitation: A Country Level Survey (SIWI, for UNDESA, 2008)
Gender-Disaggregated Data on Water and Sanitation: Expert Group Meeting Report (UN-Water, 2009)
Water and Sanitation Monitoring Platform (Ghana, Mozambique and Nigeria)
Core questions on drinking-water and sanitation for household surveys (WHO & UNICEF, 2006)
Country-led monitoring and evaluation systems: Better evidence, better policies, better development results (UNICEF, 2009)
MDG monitoring for urban water supply and sanitation: Catching up with reality in Sub-Saharan Africa (GTZ, 2007)
Expanding access to sanitation in Sub-Saharan Africa (Africa Infrastructure Country Diagnostic report, World Bank, 2008)
Moving ahead in monitoring drinking water and sanitation (joint WHO/UNICEF/UNSGAG/UN- Habitat/WSP/GTZ/SIWI/SDC presentation at the Stockholm World Water Week, 2008)
Does ‘improved’ sanitation make children healthier? Household pit latrines and child health in rural Ethiopia (Young Lives, 2009)
Extending the critical aspects of the water access indicator using East Africa as an example (International Journal of Environmental Health Research, 2009)
Water, sanitation and urban children: The need to go beyond “improved” provision (Children, Youth and Environments, 2005)
See also: The Unserved Billions


ADEQUATE WATER SUPPLIES AND ADEQUATE SANITATION

Why "adequate" rather than "improved"? Because, for water supplies, "improved" (according to the JMP definitions) only considers the type of water supply; it does not take into account water quantity, water quality, the cost of water and the (in)convenience of collecting it.

See: Adequate vs. Improved (a PowerPoint presentation on water supply in five small towns around Lake Victoria in Kenya). This is a preliminary outcome of UN-Habitat's Lake Victoria Region Water and Sanitation Initiative (see the 2008 Project Brochure and the 2004 Report).

General statistics, including WatSan
The Little Green Data Book 2009 (World Bank, 2009)
State of the World’s Children 2009 (UNICEF, 2009)
SOWC 2009 statistical tables (pdf and Excel* files)
Earlier SOWC reports
*You can try and correlate WatSan coverage, IMR, U5MR, etc. with GDP, etc.