This post starts a series of notes from guest bloggers about papers presented at the CSAE conference 2012. Tobias Lechtenfeld (University of Göttingen) summarizes the findings of a joint paper with Stephan Klasen, Kristina Meier and Johannes Rieckmann about the evaluation of a program that provides piped water in Yemen.
While the world is still celebrating the achievement of the MDG on access to save water, very little is known
about whether piped water schemes really lead to improved health outcomes. We
don't want to spoil the MDG celebrations, but the health impacts seem limited.
Take the World Bank's in-house evaluation department IEG: after reviewing
hundreds of water projects worth tens of billions of USD from the past decade, IEG concludes that "evidence of improved water quality is rare, as are indications of
the improved health of project beneficiaries".
We have been working on a large scale project in Yemen that
provides household connections to piped water and sewerage in provincial towns
in different regions of the country. Yemen is a very dry country where water resources are systematically overused - just like most other countries in the Middle East and North Africa.What came as a big surprise is that
diarrhea and other health outcomes actually increase in the treatment group,
especially among up to 5 year old children. This negative health impact appears
to be caused by frequent interruptions of water supply. During interruptions
pollutions builds up in the pipes, and the reduction of water pressure leads to
an intrusion of pollutants. In addition, some households also begin using
traditional water sources (although mixing alone does not explain why the
treatment group is worse off than the control group).
The project was implemented without choice among
beneficiaries, meaning that project areas are fully connected. That makes it a
lot easier to use quasi-experimental methods, since we don’t need to worry
about self-selection. At the same time, progress reports from the time of
construction revealed selection effects that occurred during project
implementation. We argue that these are exogenous to health outcomes and use
them as instruments.
Construction always started in the city center, so we use ‘Distance
to Center’ as first instrument. The ancient Old City was also given preference,
so we include ‘Age of House’ as second instrument. In addition, the labor
intensive construction avoided digging trenches in streets built on hard rock,
which yields our third instrument, ‘rocky ground’. Although the results are
robust to excluding the second and/or third instrument, we also provide
matching estimates, which confirm the overall picture. In addition, we use
baseline data from a small household survey that was conducted as part of the
feasibility study of the project to calculate the Diff-in-Diff effect. While
all these methods come with some caveats that are discuss in the paper,
we hope that the mix of methods provides convincing evidence on the robustness
of these health impacts.
So what goes wrong? We derive a number of hypotheses that
provide alternative explanations of water pollution that are not directly
related to piped water. We also hired a laboratory to conduct some 10,000 water
quality tests in wells, pipes, water storage tanks and drinking cups. The tests
include hard indicators, such as e.coli, but also rather soft measures, such as
total dissolved solids (TDS). We show that much of the pollution occurs in the
pipes. Nevertheless, a substantial part of water pollution also happens within
households.
Several policy conclusions emerge, which we also discussed
in several workshops with experts from donor agencies before the release of the
full evaluation report .
Most importantly, investments in piped water supply should not be made when
reliable water supply cannot be guaranteed. In such cases engaging with
existing networks of trucked water vendors (or designing public standpipes with
chlorination devices )
might generate better health outcomes at lower costs than piped house
connection. Second, water purification at point-of-use is crucial when we want
access to save water to translate into better health outcomes.
Tobias Lechtenfeld is
a research associate at the Chair of Development Economics, University of Göttingen, Germany.
Article
Klasen, Stephan,
Tobias Lechtenfeld, Kristina Meier and Johannes Rieckmann (2012). Benefits
trickling away: The health impact of extending access to piped water and
sanitation in urban Yemen. Courant Research Center Discussion Paper No. 110,
University of Göttingen, Germany
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