A seismic shift in our understanding of global water security has occurred with the publication of a groundbreaking study in Science. This research, conducted by Eawag researchers with support from leading international organizations, reveals a shocking underestimation of the crisis, doubling previous figures. Where prior estimates placed the number of people without safe drinking water at 2 billion, this novel geospatial analysis, spanning 135 low-and middle-income Countries (LMICs), now indicates a staggering 4.4 billion.
Only one in three people, in LMICs, have access to safely managed drinking water services (SMDWS). This revelation is a stark indictment of the data gaps and methodological limitations that have obscured the true scale of the problem, particularly in regions like Sub-Saharan Africa.
The study’s use of 39 covariates and advanced modeling techniques provides an unprecedented level of granularity, exposing the critical role of factors like fecal contamination and the urban-rural divide. This newly illuminated reality demands an urgent reassessment of global strategies and a renewed commitment to international cooperation, as the fight for Sustainable Development Goal, #SDG6 — access to water and sanitation for all — takes on a dramatically heightened urgency.
1. Access to water, the scale of the problem
The study (Greenwood et al., 2024) – led by Eawag researchers, with the support of ETH Zurich, United Nations Children’s Fund (UNICEF), World Health Organization (WHO), Swiss Tropical and Public Health Institute, and the University of Basel – estimates that in 2020, only 33% of the population in LMICs had access to safe water (SMDWS), leaving approximately 4.4 billion people without safe drinking water.
This figure is more than double the previous estimate of 2 billion people by the Joint Monitoring Programme (JMP) of the World Health Organization (WHO) and UNICEF. The disparity underscores the critical data gaps in global water monitoring, particularly in Sub-Saharan Africa, where some countries report less than 10% of their population using SMDWS.
Fecal contamination is identified as the primary limiting factor, affecting nearly half of the population in LMICs. This contamination is primarily measured by the presence of Escherichia coli (E. coli), a key indicator of water quality. Despite the widespread use of improved water sources — defined as those designed to deliver safe water — 48% of LMIC populations are still exposed to fecal contamination, highlighting the gap between infrastructure and actual water safety.
2. Study methodology: a geospatial approach to mapping water security
The study by Greenwood et al. (2024), published in Science, employs a geospatial modeling approach, combining household survey data from the Multiple Indicator Cluster Surveys (MICS) with global geospatial datasets.
The researchers used a random forest modeling technique to predict SMDWS use at the subnational level across 135 LMICs. The model incorporated 39 covariates, including human, climatic, hydrogeologic, biogeographic, and topographic indicators, to capture the spatial variation in SMDWS use.
The model’s performance was validated using leave-one-country-out cross-validation, achieving a coefficient of determination (R²) of 0.53, indicating that it captured 53% of the spatial variation in SMDWS use.
3. Detailed results, continent by continent
- Africa. Sub-Saharan Africa has the lowest rates of SMDWS use, with 12 countries reporting less than 10% of their population using SMDWS. In 89 subnational regions, less than 5% of the population has access to safe drinking water. Fecal contamination is the primary limiting factor, affecting over half of the population in many areas. The lack of accessibility to water on premises is also a significant issue, with over 650 million people in Sub-Saharan Africa lacking drinking water services within their households.
- Asia. Southern Asia has the highest number of people without access to SMDWS, with an estimated 1.2 billion people affected. Eastern Asia, including China, also faces significant challenges, particularly in rural areas. Fecal contamination is a major issue, with over 50% of the population in some regions exposed to contaminated water. Improved water sources are more common, but they do not always guarantee safety.
- Americas. Latin America and the Caribbean show moderate levels of SMDWS use, but significant disparities exist between urban and rural areas. Fecal contamination and lack of accessibility are the primary limiting factors. In some regions, seasonal variations in precipitation exacerbate water scarcity, leading to increased reliance on unimproved water sources.
- Europe. Eastern Europe has relatively higher rates of SMDWS use compared to other regions, but disparities exist within countries. Fecal contamination is less prevalent, but chemical contamination – particularly from arsenic, fluoride, and PFAS – poses a significant risk in some areas.
- Oceania. The Pacific Islands face unique challenges due to their geographic isolation and vulnerability to climate change. Fecal contamination and lack of accessibility are significant issues, with many communities relying on rainwater harvesting and other improvised solutions.
4. The role of environmental and socioeconomic factors
The researchers highlight the interconnected nature of environmental and socioeconomic factors in determining water security. Environmental factors such as precipitation, temperature, and vegetation play a significant role in water availability and quality. For instance, higher temperatures and increased rainfall are associated with higher levels of E. coli contamination, while seasonal variations in precipitation impact water availability.
Socioeconomic factors, including population density and urbanization, also influence access to safe water. Rural areas, characterized by low population density and limited urban infrastructure, face the greatest challenges in accessing SMDWS. This urban-rural divide is particularly pronounced in Sub-Saharan Africa, where over 650 million people lack access to drinking water on their premises, forcing many, particularly women, to spend significant time collecting water from distant sources.
5. The need for international cooperation
The findings of the Eawag’s study underscore the urgent need for international cooperation to address the global water crisis. Achieving SDG 6 requires not only financial investment but also the sharing of knowledge, technology, and best practices across borders. The study highlights the potential of Earth Observation (EO) data to complement traditional household surveys, providing a more comprehensive understanding of water security challenges.
However, the current resolution of water quality data is often limited to broad administrative areas, necessitating the collection of higher-resolution, georeferenced data to identify and address local inequalities.
Policy makers must prioritize investments in water infrastructure, particularly in rural and underserved areas, to bring drinking water closer to households. This will not only improve health outcomes but also promote gender equality by reducing the time women spend collecting water. Additionally, governance indicators such as regulatory quality and effectiveness are associated with higher estimates of SMDWS use, suggesting that strong institutions and effective policies are crucial for improving water security.
6. World Water Day
On World Water Day, March 22, the focus should shift from conflicts and arms to achieving the Sustainable Development Goals (SDGs), particularly ensuring the fundamental human right to safe and accessible drinking water for all. Pedro Arrojo-Agudo, the UN Special Rapporteur on the Human Right to Water and Sanitation, in a recent interview by the Swiss NGO Helvetas, emphasizes that access to safe water is not a charity but a democratic duty.
Arrojo-Agudo calls for governments to prioritize water as a human right, enforce stricter laws against pollution, and invest in infrastructure, particularly for marginalized communities. While progress has been made, such as constitutional recognition in some countries, implementation remains insufficient. Civil society and NGOs play a crucial role in advocating for transparency, accountability, and participatory management of water as a common good.
The UN Special Rapporteur warns against the pitfalls of privatization, which often undermines human rights and equity, and advocates for democratized public management with local involvement. World Water Day serves as a reminder to prioritize water security over conflict, ensuring no one is left behind in the pursuit of this essential human right.
7. A call to action
Access to safe drinking water is a fundamental human right, yet it remains an elusive goal for billions of people worldwide. The Eawag’s study serves as a wake-up call for the international community to mobilize resources and expertise to address the global water crisis.
The underestimation of the number of people without access to safe drinking water highlights the need for more accurate data and targeted interventions. By leveraging geospatial data and fostering international collaboration, we can identify priority areas, allocate resources effectively, and ensure that the basic human right to safe drinking water is met for all.
In conclusion, the challenge of water security in LMICs is immense, but it is not insurmountable. With concerted efforts from governments, international organizations, and civil society, we can make significant strides toward achieving SDG 6. The time to act is now — for the health, dignity, and future of billions of people worldwide.
#Égalité, #PeaceLandDignity
Dario Dongo
References
- Greenwood, E. E.; Lauber, T.; van den Hoogen, J.; Donmez, A.; Bain, R. E. S.; Johnston, R.; Crowther, T. W.; Julian, T. R. (2024). Mapping Safe Drinking Water Use in Low- and Middle-Income Countries. Science, 385(6710), 784-790. doi:10.1126/science.adh9578
- Barbara Vonarburg. Four Billion People Estimated to Lack Safe Drinking Water Services. Eawag. August 15, 2024. https://tinyurl.com/bdzj5xpa
- “I Can Make Problems Visible”. Helvetas. March 15, 2025. https://tinyurl.com/4drjjbez
Dario Dongo, lawyer and journalist, PhD in international food law, founder of WIISE (FARE - GIFT - Food Times) and Égalité.
