Approximately one billion people worldwide lack access to proper sanitation. How does this impede development, and what investments are necessary to bridge this gap?
This podcast is the sixth of a series in collaboration with J-PAL, covering their policy insights which highlight evidence on important topics in development. Read J-PAL's policy insights here - Improving sanitation access with subsidies, loans, and community-led programs.
In this episode of VoxDevTalks, Tim Phillips is joined by Karen Macours, Professor at the Paris School of Economics and co-chair of J-PAL’s health sector, to discuss J-PAL’s latest policy insight on the global sanitation crisis. The episode highlights how lack of access to safe sanitation facilities continues to impact millions worldwide, spreading disease and impeding development in low-income regions.
"There are more than 400 million people defecating in the open… [an additional] 500 million people have access to some type of facility that is really not appropriate."
Altogether, nearly a billion people worldwide are living without proper sanitation—a key barrier to achieving the UN’s goal of ending open defecation by 2030.
How poor sanitation drives disease and stunts development
The health consequences of inadequate sanitation are both severe and wide-ranging. Disease is commonly transmitted through two main pathways: direct contact with faecal matter and water contamination, which can spread parasites and trigger outbreaks of diarrhoeal illnesses such as cholera.
“Those diseases and the diarrhoea that comes with it will affect the nutritional status of children… especially during the early years of life.”
Inadequate sanitation contributes to stunted physical and cognitive development in children due to malnutrition caused by infections. Most affected areas also lack piped water, making conventional waste systems unrealistic.
Can subsidies and loans for toilet construction improve sanitation?
One of the central questions of this episode is how to make toilet construction affordable in poor communities. Macours draws on evidence from 26 randomised evaluations conducted across 14 countries, offering valuable insights into the effectiveness of sanitation interventions.
“With subsidies, the access to toilets increases. With loans, that’s mostly also true [but] it’s a little bit more mixed.”
While subsidies have consistently increased toilet access, loan-based programmes have proven less effective, as construction is not always completed.
The role of awareness and behavioural change in community-led total sanitation
Providing toilets is only part of the solution. Changing behaviour to ensure consistent and proper use is equally critical. Macours highlights the role of community-led awareness campaigns in reinforcing behavioural shifts.
“There is an approach that is called community-led total sanitation (CLTS)… What typically happens in these campaigns is the facilitator [works] with the community, [gets] community members together, [walks] through the village, pointing out where contamination may be happening and how that may be then affecting food and also drinking water.”
These interventions aim to help people see the invisible causal links between open defecation, environmental degradation, and health. While education and awareness campaigns have a generally positive effect, the results can be modest and sometimes short-lived.
Spillover effects and social dynamics in sanitation
Sanitation interventions do not occur in a vacuum—social dynamics can magnify or undermine their effectiveness. Macours outlines the complex landscape of community-wide effects, where individual decisions are influenced by others’ behaviours.
“It is indeed possible that if a household builds a latrine, and other members from a different household can use that latrine… that’s potentially a positive spillover effect.”
However, negative effects can also emerge. For instance, some individuals may choose not to invest if their neighbours do not, while others might assume it is unnecessary once the majority have already done so. Awareness campaigns may also stimulate peer pressure and mutual monitoring, encouraging continued use of facilities.
Do sanitation interventions improve health outcomes?
One of the most challenging aspects of the sanitation debate is measuring its direct impact on health. Despite improvements in access and usage, research often fails to demonstrate strong health benefits, particularly when measured by diarrhoea incidence or child health outcomes.
“We don’t always find impacts on health, even for studies that were designed to look carefully at the impacts on health.”
Self-reported diarrhoea rates can be unreliable due to increased awareness influencing survey responses, while height-for-age indicators are affected by many other variables. Still, there are signs that higher levels of sanitation coverage in communities could yield better health results.
“We may not have reached a high enough rate of toilet use or improved toilet use… so that means that the contamination continues to happen to a certain extent and possibly still too much.”
Policy implications: We need more investment in sanitation, not less
Despite mixed evidence on health impacts, Macours argues that sanitation should remain a policy priority due to the well-established biological rationale and evident market failures.
“Both policymakers and researchers are in line with the idea that we need to understand this better… because the biological foundation for this problem is clear.”
Suboptimal individual choices in the presence of externalities justify continued public investment. One policy direction involves revisiting the feasibility of piped sanitation systems, especially in urban areas where alternatives have proven inadequate.
Conclusion: Investing in sanitation is essential, even if it is complex
The episode concludes by emphasising the need to combine improved access, behavioural change, and complementary interventions to achieve larger, more sustainable impacts on sanitation. While the research is ongoing, the need for coordinated and sustained investment is undeniable.