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Indicators in Practice

Jun 23, 2015

WASH Performance Index

The WASH Performance Index provides an equitable way of assessing performance on water and sanitation metrics by comparing countries to "best-in-class" performers
WASH Performance Index score. UNC Gillings School of Global Public Health

Case Study: WASH Performance Index

Scope: Global (117 countries)

Released: 2015

Intended Audience: sustainable development and WASH communities, national governments

Potential Application: inform water and sanitation improvement planning and investments

Developer: University of North Carolina at Chapel Hill Gillings School of Global Public Health


As part of the Millennium Development Goals (MDGs), the international community set out to halve the proportion of the world’s population lacking access to safe drinking water and basic sanitation by 2015. On the global scale, this goal has been achieved for drinking water access, and progress has been made on sanitation coverage. However there is still more work to do, particularly in Sub-Saharan Africa and other developing countries. While the international community’s ultimate goal is universal access to drinking water and sanitation, differences in levels of development, infrastructure, and institutional capacity, mean some countries are farther along in achieving this goal.

The University of North Carolina’s Water, Sanitation and Hygiene (WASH) Performance Index seeks to level the playing field by evaluating performance of countries at similar levels of development. Instead of being compared to a developed country like Sweden, for instance, Bangladesh is evaluated against the performance of other countries at a similar level of development. This approach is based on the human rights principle of “progressive realization,” which means that every country should take appropriate steps towards realizing economic, social, and cultural rights, to the maximum level that their resources will allow.

How is the WASH Performance Index Score calculated?

The WASH Performance Index relies entirely on data gathered by the WHO/UNICEF Joint Monitoring Program (JMP) for Water Supply and Sanitation. Four metrics are used: water access and sanitation access (the two metrics used to evaluate MDG performance), and water equity and sanitation equity (the gap between urban and rural access).

Instead of comparing access and equity directly across countries, the Index chooses to focus on a country’s performance over time, using three data points to calculate a rate of change in performance. Then, in order to provide an equitable comparison, “best-in-class” performers are identified for differing levels of access. The closer a country’s rate of change is to the best-in-class performer’s rate of change, the better they are performing. For example, a country like Niger, which still has a large gap between urban and rural improved sanitation access (29%), and whose overall coverage was only 9% in 2012, is still seen as a top performer because it is improving its coverage more rapidly than other similar countries. Each country is given a score from -1 to 1 (a negative score indicates a negative rate of change) for each of the four metrics, which are then summed into a single performance score.

Figure 1: A country's coverage (access) and rate of change in coverage are plotted and compared to a performance frontier defined by "best-in-class" performers at that corresponding level of coverage. The closer a country is (vertically) to the performance frontier, the better their performance. UNC Gillings School of Global Public Health


Unlike for water and sanitation coverage, the WASH performance score is not correlated with GDP. In essence, the Index has decoupled a country’s stage of development from its effectiveness at providing its citizens with access to water and sanitation services. Illustrating this fact are the Index’s top performing countries, which includes some least developed countries (LDCs), Niger and Nepal.

Figure 2: The ten highest performing countries on the WASH Performance Index. UNC Gillings School of Global Public Health

In contrast to the distribution of low levels of water and sanitation access (mainly in Sub-Saharan Africa and South/Southeast Asia respectively), the performance values are distributed widely within regions [see top image]. The researchers suggest that this may be due to country-specific factors such as governance and infrastructure already in place.

Implications and Critique

The WASH Performance Index was created to address the seemingly unfair and arbitrary comparison of water and sanitation access in countries around the globe. While the Index has made for a fairer assessment of developing countries with low levels of access, the methods of comparison still seems somewhat arbitrary.

Many of the countries performing well on the index have lots of work left to do. Some high scoring countries still have low levels of access and equity (see the previous example of Niger). Scoring highly is not an indication of a country’s stellar water sanitation and hygiene services, but instead should affirm that recent steps taken to improve WASH access and equity may be working, at least in comparison to other countries.

The implications of a country’s performance score might also vary for countries at different levels of access. In Niger, improvements in access and equity of access may result in fewer premature deaths from diarrheal diseases. In a country with higher levels of access, further improvements may have smaller impacts.

The real value of the WASH Performance Index may lie in its ability to help inform the type of WASH investments needed in a country based on its current level of access and its performance through time. Some countries may need to invest in capacity building, while others farther along may be looking to expand a WASH project’s reach. Figure 3 illustrates how the Index could be used to inform future WASH planning and investment, though it’s unclear how much insight this provides beyond the current JMP data.


Figure 3: Targeted investment based on current coverage and trends in coverage over time. UNC Gillings School of Global Public Health