Bulletin of the World Health Organization

Accounting for water quality in monitoring access to safe drinking-water as part of the Millennium Development Goals: lessons from five countries

Rob ES Bain, Stephen W Gundry, Jim A Wright, Hong Yang, Steve Pedley & Jamie K Bartram

Volume 90, Number 3, March 2012, 228-235A

Table 4. Effect of study assumptions on the estimated percentage of the population with access to safe drinking-water

Study assumption Effect on estimated percentage with access to safe drinking-water
No contamination occurred between the water source and the point of use. Overestimation
The percentage of water sources found to comply with WHO drinking-water safety guidelines at a single survey date remained constant for a year. Overestimation, particularly for nitrates and thermotolerant coliform bacteria
All untested types of improved water sourcea complied with WHO drinking-water safety guidelines. Overestimation
All water sources complied with WHO drinking-water safety guidelines on parameters not measured in the RADWQ project.b Overestimation
All unimproved water sources did not comply with WHO drinking-water safety guidelines. Underestimation
No account was taken of household water treatment and safe storage. Underestimation
The percentage of water sources that complied with WHO drinking-water safety guidelines remained constant before and after the RADWQ project.c Unclear but country-specific
The percentage of water sources that complied with WHO drinking-water safety guidelines was the same in urban and rural areas for each source type. Unclear but country-specific

RADWQ, Rapid Assessment of Drinking-water Quality; WHO, World Health Organization.

a Types of improved water source used by less than 5% of a country’s population were not sampled during the RADWQ project.

b The RADWQ project tested water sources for the presence of thermotolerant coliform bacteria, fluoride, arsenic and nitrate compounds.

c The RADWQ project was carried out between October 2004 and April 2005.