S ALVADOR
Impact Estimates Using Panel Data from 2011 to 2013
with Maureen Cropper and Raymond Guiteras Summary
Adequate and dependable access to water and sanitation is needed to sustain humanity and to promote growth and development. For the rural poor access to water is essential both for basic needs and for productive purposes. Safe drinking-water and sanitation are crucial to human welfare. The Millennium Development Declaration in 2000 called for the world to halve, by 2015, the proportion of people without access to safe drinking water as well as the proportion of people who do not have access to basic sanitation. Yet in 2015, millions still did not have access to improved drinking-water sources or have access to improved sanitation, such as toilets or latrines.
This essay quantifies the benefits of a set of water, sanitation and hygiene interventions, that included community training campaigns, and the construction or improvement of water and sanitation systems in communities across the Northern Zone of El Salvador between 2006 and 2012 to advance this millennium development goal. The goal of the water and sanitation investments was to enhance access to water systems and to improve sanitation services for the poorest by providing piped water or (in a few cases) public taps for households that previously did not have access to this level of service and latrines to all water project participants who do not already have improved sanitation. The impact of the interventions was measured using a rigorous quasi-experimental methodology that used a matched difference-in-differences estimator with a three-year (2011-2013) panel household survey specifically designed to evaluate the impact these investments.
Our impact analysis suggests that the water, sanitation and hygiene interventions resulted in significant improvements in access to safe water and improved sanitation. We found robust and significant benefits across measures of access to water and sanitation, an increase of 3 percentage point in access to improved sanitation and of 25 percentage points in access to improved water sources in treatment communities. We found reductions in the time to reach improved water sources (2 minutes), increases in ownership and use of improved water and sanitation services, 28 percentage points more likely to use tap water as a principal source for drinking water, increases in the reliability of service with 16.5 hours per week more of service in treatment communities. Other impacts include: increases in satisfaction with the water system in the community, reductions in the perceived riskiness of drinking water from water systems.
We found a decrease the probability of having bacterial contamination at the source. Treatment households are between 16 and 19 percentage points less likely to have E.coli in their water source after but there are no effects on the water stored or at the point of consumption. This indicates the drinking water is being contaminated between the source and the point of consumption. We also found that expenditure on water increased by 1.87 USD per month, on average, among beneficiary households following the installation of metered water taps. The reductions in the time spent carrying water and doing laundry outside the home were significant. On average, individuals saved 1.41 hours per week carrying water thanks to the interventions and up to 2.75 for households that report being direct beneficiaries. The decrease in time spent doing laundry outside the home was on average 1.79 hours per week were concentrated and significant for females.
Exploring how these effects differ by the amount of time beneficiary households were connected to the new or improved system, we found that these effects occur within the first months of being connected and that among households that were connected for a longer time-period, these effects persist; indicative of the sustainability of community-demand driven rural water and sanitation infrastructure projects.
Keywords: water and sanitation, impact evaluation, matching, panel data, El Salvador
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I NTRODUCTION
The importance of water and sanitation infrastructure for economic growth and development in general has long been recognized. Throughout history people have settled near water sources to use this resource for human consumption, sanitation services, irrigation and food production, etc. The economic and social returns from investments in water and sanitation systems are high and reflected through increased economic security and reductions in health risks, increased resilience of the poor to disease and climate shocks, and ultimately poverty reduction. For the rural poor, who make up some 75% of the world’s poorest people, access to water is essential both for basic needs and for productive purposes. The consumption of unsafe water impairs human health through illnesses such as diarrhea, and untreated sewage can contaminate drinking-water supplies and the environment, creating a heavy burden on communities.
The Millennium Development Declaration in 2000 called20 for the world to halve, by 2015, the proportion of people without access to safe drinking water as well as the proportion of people who do not have access to basic sanitation. However, by 2015, the WHO/UNICEF Joint Monitoring Programme (JMP) estimated that 660 million people still did not have access to improved drinking-water sources, 1.8 billion people were estimated to drink water that is faecally contaminated and over 2.4 billion people do not have access to improved sanitation, such as toilets or latrines21.
This essay quantifies the benefits of a set of water, sanitation and hygiene interventions, that included community training campaigns, and the construction or improvement of water and sanitation systems in communities across the Northern Zone of El Salvador between 2006 and 2012 to advance this millennium development goal.
The conditions in the area were these interventions took place were some of the worst in the country. Half of the poorest municipalities in El Salvador are in the Northern Zone and suffered more damage from the country’s internal conflict during the 1980s than any other region. In 2007, the economic and social indicators in the Northern Zone were worse than the national average: 44.7 percent of households in the Northern Zone were poor, compared with the 34.6 percent national estimate; 17.2 percent of households in the region lived in extreme poverty in 2007 compared with 10.8 percent at the national level. Human capital development was also lower in this region than in any other. The average level of schooling in El Salvador was 5.9 years in 2007, while the average in the Northern Zone was only 4.3 years. The percentage of illiterate people in the Northern Zone was 18.3 percent in 2007 versus an 11.1 percent national average.22
The goal of these water and sanitation and hygiene (WASH) interventions was to enhance access to water systems and to improve sanitation services for the poorest by providing piped water or (in a few cases) public taps for households that previously did not have access to this level of service and latrines to all water project participants who do not already have improved sanitation. In addition, the interventions included greases traps for all beneficiary households to manage gray waters.
Household water demand for different uses is determined by the time, labor and financial costs required to access water. Since households in the Northern Zone had access to multiple sources of water and different levels of service, in this evaluation, we gave priority to the measurement of changes in expenses to access water of adequate quality for different needs and the time costs associated with lack of access adequate quality water sources. One reason for this is that these costs accounted for the bulk of the expected benefits of
20 United Nations Millennium Development Goals. 2000. http://www.un.org/millenniumgoals/
21 http://www.un.org/sustainabledevelopment/water-and-sanitation
22 Source: (DIGESTYC, 2007).
81 water supply interventions in the economic analysis underlying the program23. We did not focus on the effects on health because the diarrhea rates in El Salvador dropped substantially in the years leading up to the intervention. This makes measuring changes in rates more difficult and costlier, and is likely to mean lower-than-expected benefits from health improvements in these projects. We would have needed a very large sample size to detect any impact on self-reported health outcomes
Given the different types of interventions included in this WASH package, we included outcome indicators that would be affected by different aspects of the interventions and evaluate the impact of the interventions as a package. We included indicators such as expenses in water and time spent dealing with lack of access to reliable water sources, as mentioned before, and reliability, satisfaction of water services and water contamination for the water infrastructure component; for the sanitation infrastructure component, we included access to improved sanitation infrastructure; and for the hygiene campaign component we included frequency of hand washing, knowledge of diarrhea prevention and food handling practices.
This essay lays out the results of the impact evaluation of the WASH interventions. Using a baseline and two follow-up surveys, specifically designed to evaluate the impact these investments, that was administered24 from March to April of 2011, 2012, and 2013, respectively. The benefits of the water and sanitation projects are measured with a rigorous quasi-experimental design that incorporates matching, a panel survey and difference-in-differences (DID) estimations. To the extent possible, we examined the distribution of benefits and outcomes across gender and socio-economic groups.
In addition, we exploit the different dates that the WASH interventions were finalized to explore the sustainability of the observed impacts. By the time of the first follow-up survey in 2012, not all projects had been finalized and by the end line survey while all interventions were finalized. This implies that treatment households were connected to the new and/or improved systems for different lengths of time, which allows us to explore differences in the time between finalization of the interventions and the dates of the survey. This analysis allows us to explore the sustainability of the benefits and of the observed impacts.
This study contributes to the WASH literature in three ways. First, we examine the effect of an at-scale community-demand driven WASH intervention across a comprehensive set of indicators in a setting where the interventions mainly increase the quantity and quality of water and sanitation access. The examples in the WASH literature are often in the context of open defecation and were access to water is mainly through natural water sources. Our study present novel evidence on the effects of improving water and sanitation access through WASH intervention in a setting where water system existed but not of adequate quality. The evidence in this study from rural areas in El Salvador provides context and the opportunity to adjust the expectation on the effect of WASH intervention in other part of Latin America and the world where the initial condition of water and sanitation access are similar. By focusing on the costs of collecting, storing, and treating water, the perceptions and satisfaction of the beneficiaries, and the dynamics of the time reallocation caused by increased access to adequate water, we provide evidence on different mechanisms and benefits of WASH interventions that can be included in the cost benefit calculus of decision-makers at the time of deciding what interventions to fund.
Second, we provide evidence on the literature on the importance of research design at the early stages of impact evaluation to avoid relying on ex-post statistical methods selection, which have been recently showed to perform poorly in replicating known experimental impacts. The combination of pre-baseline matching and
23 In the economic analysis prepared for the water and sanitation component, three-quarters of the expected benefits were attributed to reductions in coping costs, specifically the time costs associated with collecting water and the monetary cost of relying on alternative water sources (such as vendors) and storage systems.
24 Data collection for the panel survey was implemented by the Dirección General de Estadísticas y Censos General (DIGESTYC) , the statistical agency of El Salvador.
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panel data in this study provides a methodologically well-grounded example of the impacts of WASH interventions in a literature that is plagued by short-comings due to intervention placement bias and the endogeneity of households’ WASH choices that are a function of where they live.
Third we present novel evidence on the effects of WASH interventions on the quality of drinking water at the source and at the point of consumption. Contamination of drinking water from the source to the point of consumption is a persistent problem in developing countries. This study is one of the few in the literature that estimates the effects of WASH interventions on source and stored water over time and with significantly larger sample size. In addition, to identifying this bottleneck in the provision of safe water in a diverse set of rural communities, we provide evidence on how this point of distribution to point of consumption contamination is affected by WASH interventions. To our knowledge, this study is the first that estimates the impact of a large WASH intervention on the degree of contamination at the source versus at the point of consumption.