There are sound reasons to include both a Drinking Water and an Adequate Sanitation indicator in Environmental Health measurement. The WHO identifies diarrhea as the disease most attributable to quality of the local environment. It is estimated that environment factors account for 94% of the global disease burden for diarrhea (WHO 2006). Measures of Drinking Water and Adequate Sanitation correlate well with diarrheal diseases. One of the main causes of diarrheal disease is contamination by fecal-oral pathogens, which is largely caused by inadequate drinking water and sanitation infrastructure. The WHO has estimated that 88% of diarrhea cases result from the combination of unsafe drinking water, inadequate sanitation, and improper hygiene (WHO 2006 and Pruss-Ustun 2004a).
The 2008 EPI uses Drinking Water and Adequate Sanitation indicators from WHO Country Profiles on the Environmental Burden of Disease. The dataset used for the Drinking Water indicator records the percentage of a country’s population with access to an improved drinking water source. Although this metric does not perfectly capture the quality of water that individuals receive, it is the best available for measurement of exposure to environmental risk. The WHO dataset used for the Adequate Sanitation indicator calculates the percentage of a country’s population with access to an improved source of sanitation. Again, this metric is used to estimate the environmental risk individuals face from exposure to poor sanitation. The assumption is that those with access to adequate sanitation facilities are less likely to come into contact with bacteria and viruses that can cause them harm than those without such facilities.
The targets for the Drinking Water and Adequate Sanitation indicators are both set at 100% (derived from UN Millennium Development Goal (MDG) 7, Target 10, and Indicators 30 and 31, respectively). This target reflects the belief that every person ought to have access to safe drinking water and adequate sanitation. Many developed countries have already achieved this target, indicating that 100% coverage is not an unrealistic expectation.
Each dot in the histogram is a single country’s proximity-to-target score for this indicator. The tinted box represents the inner quartile range of country values, or points lying between the 25th and 75th percentiles. The small triangle marker at the bottom of the chart indicates the median of country scores.
